Claims for Patent: 9,586,955

Summary for Patent: 9,586,955

Title:	Compounds for treating spinal muscular atrophy
Abstract:	Provided herein are compounds of Formula (I): ##STR00001## and forms thereof, including compositions thereof and uses therewith for treating spinal muscular atrophy.
Inventor(s):	Qi; Hongyan (Plainsboro, NJ), Choi; Soongyu (Belle Mead, NJ), Dakka; Amal (Whitehouse Station, NJ), Karp; Gary Mitchell (Princeton Junction, NJ), Narasimhan; Jana (Scotch Plains, NJ), Naryshkin; Nikolai (East Brunswick, NJ), Turpoff; Anthony A. (Hillsborough, NJ), Weetall; Marla L. (Morristown, NJ), Welch; Ellen (Califon, NJ), Woll; Matthew G. (Dunellen, NJ), Yang; Tianle (Mountainside, NJ), Zhang; Nanjing (Princeton, NJ), Zhang; Xiaoyan (Belle Mead, NJ), Zhao; Xin (Belle Mead, NJ), Green; Luke (Basel, CH), Pinard; Emmanuel (Linsdort, FR), Ratni; Hasane (Habsheim, FR)
Assignee:	PTC Therapeutics, Inc. (South Plainfield, NJ) F. Hoffmann-La Roche AG (Basel, CH)
Application Number:	14/377,531
Patent Claims:	1. A compound of Formula (IIa1): ##STR00473## or a form thereof, wherein: R.sub.1 is heterocyclyl; wherein, heterocyclyl is optionally substituted with one, two or three R.sub.3 substituents and optionally, with one additional R.sub.4 substituent; or, wherein, heterocyclyl is optionally substituted with one, two, three or four R.sub.3 substituents; R.sub.2 is heteroaryl; wherein, heteroaryl is optionally substituted with one, two or three R.sub.6 substituents and optionally, with one additional R.sub.7 substituent; R.sub.a is, in each instance, independently selected from hydrogen, halogen or C.sub.1-8alkyl; R.sub.b is hydrogen, halogen, C.sub.1-8alkyl or C.sub.1-8alkoxy; R.sub.c is hydrogen, halogen or C.sub.1-8alkyl; R.sub.3 is, in each instance, independently selected from cyano, halogen, hydroxy, oxo, C.sub.1-8alkyl, halo-C.sub.1-8alkyl, C.sub.1-8alkyl-carbonyl, C.sub.1-8alkoxy, halo-C.sub.1-8alkoxy, C.sub.1-8alkoxy-C.sub.1-8alkyl, C.sub.1-8alkoxy-carbonyl, amino, C.sub.1-8alkyl-amino, (C.sub.1-8alkyl).sub.2-amino, amino-C.sub.1-8alkyl, C.sub.1-8alkyl-amino-C.sub.1-8alkyl, (C.sub.1-8alkyl).sub.2-amino-C.sub.1-8alkyl, amino-C.sub.1-8alkyl-amino, C.sub.1-8alkyl-amino-C.sub.1-8alkyl-amino, (C.sub.1-8alkyl-amino-C.sub.1-8alkyl).sub.2-amino, (C.sub.1-8alkyl).sub.2-amino-C.sub.1-8alkyl-amino, [(C.sub.1-8alkyl).sub.2-amino-C.sub.1-8alkyl].sub.z-amino, (C.sub.1-8alkyl-amino-C.sub.1-8alkyl)(C.sub.1-8alkyl)amino, [(C.sub.1-8alkyl).sub.2-amino-C.sub.1-8alkyl](C.sub.1-8alkyl)amino, C.sub.1-8alkoxy-C.sub.1-8alkyl-amino, (C.sub.1-8alkoxy-C.sub.1-8alkyl).sub.2-amino, (C.sub.1-8alkoxy-C.sub.1-8alkyl)(C.sub.1-8alkyl)amino, C.sub.1-8alkyl-carbonyl-amino, C.sub.1-8alkoxy-carbonyl-amino, hydroxy-C.sub.1-8alkyl, hydroxy-C.sub.1-8alkoxy-C.sub.1-8alkyl, hydroxy-C.sub.1-8alkyl-amino, (hydroxy-C.sub.1-8alkyl).sub.2-amino or (hydroxy-C.sub.1-8alkyl)(C.sub.1-8alkyl)amino; R.sub.4 is C.sub.3-14cycloalkyl, C.sub.3-14cycloalkyl-C.sub.1-8alkyl, C.sub.3-14cycloalkyl-amino, aryl-C.sub.1-8alkyl, aryl-C.sub.1-8alkoxy-carbonyl, aryl-sulfonyloxy-C.sub.1-8 alkyl, heterocyclyl or heterocyclyl-C.sub.1-8alkyl; wherein, each instance of C.sub.3-14cycloalkyl, aryl and heterocyclyl is optionally substituted with one, two or three R.sub.5 substituents; R.sub.5 is, in each instance, independently selected from halogen, hydroxy, cyano, nitro, C.sub.1-8alkyl, halo-C.sub.1-8alkyl, C.sub.1-8alkoxy, halo-C.sub.1-8alkoxy, amino, C.sub.1-8alkyl-amino, (C.sub.1-8alkyl).sub.2-amino or C.sub.1-8alkyl-thio; R.sub.6 is, in each instance, independently selected from halogen, hydroxy, cyano, nitro, C.sub.1-8alkyl, C.sub.2-8alkenyl, halo-C.sub.1-8alkyl, hydroxy-C.sub.1-8alkyl, C.sub.1-8alkoxy, halo-C.sub.1-8alkoxy, C.sub.1-8alkoxy-C.sub.1-8alkyl, amino, C.sub.1-8alkyl-amino, (C.sub.1-8alkyl).sub.2-amino or C.sub.1-8alkyl-thio; and, R.sub.7 is C.sub.3-14cycloalkyl, C.sub.3-14cycloalkyl-oxy, aryl, heterocyclyl or heteroaryl. 2. The compound of claim 1, wherein R.sub.3 is C.sub.1-8alkyl selected from methyl, ethyl, propyl, isopropyl and tert-butyl. 3. The compound of claim 1, wherein R.sub.6 is C.sub.1-8alkyl selected from methyl, ethyl, propyl, isopropyl and tert-butyl. 4. The compound of claim 1, wherein R.sub.a is, in each instance, hydrogen. 5. The compound of claim 1, wherein R.sub.b is C.sub.1-8alkyl. 6. The compound of claim 1, wherein R.sub.c is hydrogen or C.sub.1-8alkyl. 7. The compound of claim 1, wherein the form is selected from a free acid, free base, salt, isotopologue, stereoisomer, racemate, enantiomer, diastereomer or tautomer thereof. 8. The compound of claim 7, wherein the salt form is a chloride, hydrobromide, hydrochloride, dihydrochloride, acetate, trifluoroacetate or trifluoroacetic acid salt. 9. The compound of claim 1, wherein the compound is selected from the group consisting of: 2-(6-methylimidazo[1,2-a]pyridin-2-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a- ]pyrimidin-4-one, 2-(6-methylimidazo[1,2-a]pyrazin-2-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a- ]pyrimidin-4-one, 2-(6-methylimidazo[1,2-a]pyrazin-2-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(6-methoxypyridin-3-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyrimidin-4-- one, 2-(5-fluoropyridin-3-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyrimidin- -4-one, 2-(5-fluoropyridin-3-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(5-chloropyridin-3-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyrimidin-4-o- ne, 2-(5-chloropyridin-3-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(5-chloro-6-methoxypyridin-3-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyr- imidin-4-one, 2-(1H-indol-6-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(1H-indol-5-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(imidazo[1,2-a]pyridin-7-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyrimid- in-4-one, 2-(imidazo[1,2-a]pyridin-6-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-- a]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-6-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a- ]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-6-yl)-7-(4-methylpiperazin-1-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1,4-diazepan-1-yl)-2-(2-methylimidazo[1,2-a]pyridin-6-yl)-4H-pyrido[1,- 2-a]pyrimidin-4-one, 7-[(3R,5 S)-3,5-dimethylpiperazin-1-yl]-2-(2-methylimidazo[1,2-a]pyridin-6-yl)-4H-- pyrido[1,2-a]pyrimidin-4-one, 2-(6, 8-dimethylimidazo[1,2-a]pyrazin-2-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]- pyrimidin-4-one, 2-(6,8-dimethylimidazo[1,2-a]pyrazin-2-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4, 6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a- ]pyrimidin-4-one, 2-(4, 6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(piperazin-1-yl)-2-[2-(trifluoromethyl)imidazo[1,2-a]pyridin-6-yl]-4H-p- yrido[1,2-a]pyrimidin-4-one, 2-(2-ethylimidazo[1,2-a]pyridin-6-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]- pyrimidin-4-one, 2-(2,3-dimethylimidazo[1,2-a]pyridin-6-yl)-7-(piperazin-1-yl)-4H-pyrido[1- ,2-a]pyrimidin-4-one, 7-(piperazin-1-yl)-2-(1H-pyrrolo[2,3-b]pyridin-5-yl)-4H-pyrido[1,2-a]pyri- midin-4-one, 2-(1-methyl-1H-pyrrolo[2,3-b]pyridin-5-yl)-7-(piperazin-1-yl)-4H-pyrido[1- ,2-a]pyrimidin-4-one, 7-[(3R,5 S)-3,5-dimethylpiperazin-1-yl]-2-(1-methyl-1H-pyrrolo[2,3-b]pyridin-5-yl)- -4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R,5 S)-3,5-dimethylpiperazin-1-yl]-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1,4-diazepan-1-yl)-2-(4,6-dimethylpyrazolo[1, 5-a]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methyl-1,3-benzoxazol-6-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyrim- idin-4-one, 2-(2-methyl-1,3-benzoxazol-6-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methyl-1,3-benzothiazol-5-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methyl-1,3-benzothiazol-5-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyr- imidin-4-one, 2-(2-methyl-2H-indazol-5-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyrimidin- -4-one, 2-(2-methyl-2H-indazol-5-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2, 8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]- pyrimidin-4-one, 2-(2-methyl-1,3-benzoxazol-5-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyrim- idin-4-one, 2-(2-methyl-1,3-benzoxazol-5-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1,4-diazepan-1-yl)-2-(2-methyl-1,3-benzothiazol-5-yl)-4H-pyrido[1,2-a]- pyrimidin-4-one, 7-[(3 S)-3-methylpiperazin-1-yl]-2-(4-methyl-1,3-thiazol-2-yl)-4H-pyrido[1,2-a]- pyrimidin-4-one, 2-(4-methyl-1,3-thiazol-2-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyrimidi- n-4-one, 7-(4-methyl-1,4-diazepan-1-yl)-2-(2-methylimidazo[1,2-a]pyridin-6- -yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(4-methylpiperazin-1-yl)-4H- -pyrido[1,2-a]pyrimidin-4-one, 2-(2-methyl-1,3-benzoxazol-6-yl)-7-(4-methylpiperazin-1-yl)-4H-pyrido[1,2- -a]pyrimidin-4-one, 7-[(3R,5 S)-3,5-dimethylpiperazin-1-yl]-2-(2-methyl-1,3-benzoxazol-6-yl)-4H-pyrido- [1,2-a]pyrimidin-4-one, 2-(5-fluoro-6-methoxypyridin-3-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R,5 S)-3,5-dimethylpiperazin-1-yl]-2-(5-fluoro-6-methoxypyridin-3-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 7-[(3R,5 S)-3,5-dimethylpiperazin-1-yl]-2-(2-methyl-1,3-benzothiazol-5-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 2-(2-methyl-1,3-benzothiazol-5-yl)-7-(4-methylpiperazin-1-yl)-4H-pyrido[1- ,2-a]pyrimidin-4-one, 2-(2-methyl-1,3-benzothiazol-5-yl)-7-(4-methyl-1,4-diazepan-1-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 7-[(8aS)-hexahydropyrrolo[1,2-a]pyrazin-2(1H)-yl]-2-(2-methyl-1,3-benzoth- iazol-5-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-methyl-1H-imidazol-1-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyrimidi- n-4-one, 2-(4-methyl-1H-imidazol-1-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(5-fluoro-6-methoxypyridin-3-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyr- imidin-4-one, 7-[(3 S)-3-methylpiperazin-1-yl]-2-(1-methyl-1H-pyrazol-4-yl)-4H-pyrido[1,2-a]p- yrimidin-4-one, 2-(1-methyl-1H-pyrazol-4-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyrimidin- -4-one, 2-(2-methyl-1,3-benzoxazol-6-yl)-7-[(3R)-3-methylpiperazin-1-yl]-4- H-pyrido[1,2-a]pyrimidin-4-one, 7-(3,3-dimethylpiperazin-1-yl)-2-(2-methyl-1,3-benzoxazol-6-yl)-4H-pyrido- [1,2-a]pyrimidin-4-one, 7-(1,4-diazepan-1-yl)-2-(2-methyl-1,3-benzoxazol-6-yl)-4H-pyrido[1,2-a]py- rimidin-4-one, 2-(2-methyl-1,3-benzoxazol-6-yl)-7-(4-methyl-1,4-diazepan-1-yl)-4H-pyrido- [1,2-a]pyrimidin-4-one, 7-[(8aS)-hexahydropyrrolo[1,2-a]pyrazin-2(1H)-yl]-2-(2-methyl-1,3-benzoxa- zol-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(8aR)-hexahydropyrrolo[1,2-a]pyrazin-2(1H)-yl]-2-(2-methyl-1,3-benzoxa- zol-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,5-dimethoxypyridin-2-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyrimidi- n-4-one, 7-(4-ethylpiperazin-1-yl)-2-(2-methyl-1,3-benzoxazol-6-yl)-4H-pyr- ido[1,2-a]pyrimidin-4-one, 2-(8-fluoro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(piperazin-1-yl)-4H-pyr- ido[1,2-a]pyrimidin-4-one, 7-[(3R,5 S)-3,5-dimethylpiperazin-1-yl]-2-(8-fluoro-2-methylimidazo[1,2-a]pyridin-- 6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-fluoro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(4-methyl-1,4-diazepan-- 1-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methyl-1,3-benzothiazol-6-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyr- imidin-4-one, 2-(2-methyl-1,3-benzothiazol-6-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(6-methoxypyridin-2-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyrimidin-4-- one, 7-(piperazin-1-yl)-2-(pyridin-3-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(5-methoxypyridin-3-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyrimidin-4-- one, 7-[(3 S)-3,4-dimethylpiperazin-1-yl]-2-(2-methyl-1,3-benzoxazol-6-yl)- -4H-pyrido[1,2-a]pyrimidin-4-one, 7-[4-(dimethylamino)piperidin-1-yl]-2-(2-methyl-1,3-benzoxazol-6-yl)-4H-p- yrido[1,2-a]pyrimidin-4-one, 7-[(3 S)-3-(dimethylamino)pyrrolidin-1-yl]-2-(2-methyl-1,3-benzoxazol-6-yl)-4H-- pyrido[1,2-a]pyrimidin-4-one, 7-(4-aminopiperidin-1-yl)-2-(2-methyl-1,3-benzoxazol-6-yl)-4H-pyrido[1,2-- a]pyrimidin-4-one, 7-[(3 aR,6aS)-hexahydropyrrolo[3,4-c]pyrrol-2(1H)-yl]-2-(2-methyl-1,3-benzoxazo- l-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-3,4-dimethylpiperazin-1-yl]-2-(2-methyl-1,3-benzoxazol-6-yl)-4H-p- yrido[1,2-a]pyrimidin-4-one, 7-(1,4-diazepan-1-yl)-2-(2-methyl-1,3-benzothiazol-6-yl)-4H-pyrido[1,2-a]- pyrimidin-4-one, 2-(2-methyl-1,3-benzothiazol-6-yl)-7-(4-methyl-1,4-diazepan-1-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 7-[(8aS)-hexahydropyrrolo[1,2-a]pyrazin-2(1H)-yl]-2-(2-methyl-1,3-benzoth- iazol-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methyl-1,3-benzothiazol-6-yl)-7-(4-methylpiperazin-1-yl)-4H-pyrido[1- ,2-a]pyrimidin-4-one, 7-[(3 S)-3,4-dimethylpiperazin-1-yl]-2-(4,6-dimethylpyrazolo[1, 5-a]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3R,5 S)-3,4,5-trimethylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-3-(dimethylamino)pyrrolidin-1-yl]-2-(2-methyl-1,3-benzoxazol-6-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-ethyl-1,3-benzoxazol-6-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyrimi- din-4-one, 2-(2-ethyl-1,3-benzoxazol-6-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methyl-1,3-benzoxazol-6-yl)-7-[(3 aR,6aS)-5-methylhexahydropyrrolo[3,4-c]pyrrol-2(1H)-yl]-4H-pyrido[1,2-a]p- yrimidin-4-one, 2-(8-fluoro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(4-methylpiperazin-1-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-fluoro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3R)-3-methylpiperazin- -1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-fluoro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(8aS)-hexahydropyrrolo- [1,2-a]pyrazin-2(1H)-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-fluoro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(8aR)-hexahydropyrrolo- [1,2-a]pyrazin-2(1H)-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(4-aminopiperidin-1-yl)-2-(8-fluoro-2-methylimidazo[1,2-a]pyridin-6-yl)- -4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-3-(dimethylamino)pyrrolidin-1-yl]-2-(8-fluoro-2-methylimidazo[1,2- -a]pyridin-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3 S)-3-(dimethylamino)pyrrolidin-1-yl]-2-(8-fluoro-2-methylimidazo[1,2-a]py- ridin-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(3,3-dimethylpiperazin-1-yl)-2-(2-methyl-1,3-benzothiazol-6-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 7-[(8aR)-hexahydropyrrolo[1,2-a]pyrazin-2(1H)-yl]-2-(2-methyl-1,3-benzoth- iazol-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[4-(dimethylamino)piperidin-1-yl]-2-(2-methyl-1,3-benzothiazol-6-yl)-4H- -pyrido[1,2-a]pyrimidin-4-one, 2-(2-methyl-1,3-benzothiazol-6-yl)-7-(piperidin-4-yloxy)-4H-pyrido[1,2-a]- pyrimidin-4-one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(piperazin-1-yl)-4H-pyr- ido[1,2-a]pyrimidin-4-one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3R,5 S)-3,5-dimethylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(4-methyl-1,4-diazepan-- 1-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3R)-3-methylpiperazin- -1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(8aR)-hexahydropyrrolo- [1,2-a]pyrazin-2(1H)-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(8aS)-hexahydropyrrolo- [1,2-a]pyrazin-2(1H)-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3 S)-3,4-dimethylpiperazin-1-yl]-2-(8-fluoro-2-methylimidazo[1,2-a]pyridin-- 6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-3,4-dimethylpiperazin-1-yl]-2-(8-fluoro-2-methylimidazo[1,2-a]pyr- idin-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[4-(dimethylamino)piperidin-1-yl]-2-(8-fluoro-2-methylimidazo[1,2-a]pyr- idin-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-fluoro-2-methyl-1,3-benzoxazol-6-yl)-7-(1,2,3,6-tetrahydropyridin-4-- yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-fluoro-2-methyl-1,3-benzoxazol-6-yl)-7-(1-methyl-1,2, 3,6-tetrahydropyridin-4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methyl-1,3-benzoxazol-6-yl)-7-(1,2,3,6-tetrahydropyridin-4-yl)-4H-py- rido[1,2-a]pyrimidin-4-one, 2-(2-methyl-1,3-benzoxazol-6-yl)-7-(1-methyl-1,2,3,6-tetrahydropyridin-4-- yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1-ethyl-1,2,3,6-tetrahydropyridin-4-yl)-2-(2-methyl-1,3-benzoxazol-6-y- l)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-fluoro-2-methyl-1,3-benzoxazol-6-yl)-7-(piperazin-1-yl)-4H-pyrido[1,- 2-a]pyrimidin-4-one, 2-(4-fluoro-2-methyl-1,3-benzoxazol-6-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3 S)-3,4-dimethylpiperazin-1-yl]-2-(4-fluoro-2-methyl-1,3-benzoxazol-6-yl)-- 4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-fluoro-2-methyl-1,3-benzoxazol-6-yl)-7-(4-methylpiperazin-1-yl)-4H-p- yrido[1,2-a]pyrimidin-4-one, 7-(4-ethylpiperazin-1-yl)-2-(4-fluoro-2-methyl-1,3-benzoxazol-6-yl)-4H-py- rido[1,2-a]pyrimidin-4-one, 2-(4-fluoro-2-methyl-1,3-benzoxazol-6-yl)-7-(4-propylpiperazin-1-yl)-4H-p- yrido[1,2-a]pyrimidin-4-one, 7-(1-ethyl-1,2,3,6-tetrahydropyridin-4-yl)-2-(4-fluoro-2-methyl-1,3-benzo- xazol-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-fluoro-2-methyl-1,3-benzoxazol-6-yl)-7-(1-propyl-1,2,3,6-tetrahydrop- yridin-4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3 S)-3,4-dimethylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1, 5-a]pyrazin-2-yl)-7-(4-methyl-1,4-diazepan-1-yl)-4H-pyrido[1,2-a]pyrimidi- n-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3R)-3-methylpiper- azin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(8aS)-hexahydropyrrolo[1,2- -a]pyrazin-2(1H)-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(8aR)-hexahydropyrrolo[1,2- -a]pyrazin-2(1H)-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(4-ethylpiperazin-1-yl)-4H-- pyrido[1,2-a]pyrimidin-4-one, 7-[4-(dimethylamino)piperidin-1-yl]-2-(4,6-dimethylpyrazolo[1, 5-a]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(3,3-dimethylpiperazin-1-yl)-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(4-cyclopropylpiperazin-1-yl)-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-y- l)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1,2,3,6-tetrahydropyridin-- 4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3R)-4-ethyl-3-methylpiper- azin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[4-(dimethylamino)piperidin-1-yl]-2-(2-methyl-1,3-benzothiazol-5-yl)-4H- -pyrido[1,2-a]pyrimidin-4-one, 7-(4-aminopiperidin-1-yl)-2-(2-methyl-1,3-benzothiazol-5-yl)-4H-pyrido[1,- 2-a]pyrimidin-4-one, 7-[(3 aR,6aS)-hexahydropyrrolo[3,4-c]pyrrol-2(1H)-yl]-2-(2-methyl-1,3-benzothia- zol-5-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-methyl-1,2,3,6-tetrahydr- opyridin-4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-ethyl-1,2,3,6-tetrahydro- pyridin-4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-propyl-1,2,3,6-tetrahydr- opyridin-4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1-cyclopropyl-1,2,3,6-tetrahydropyridin-4-yl)-2-(4,6-dimethylpyrazolo[- 1,5-a]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[1-(propan-2-yl)-1,2,3,6-te- trahydropyridin-4-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1-cyclobutyl-1,2,3,6-tetrahydropyridin-4-yl)-2-(4,6-dimethylpyrazolo[1- ,5-a]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[1-(oxetan-3-yl)-1,2,3,6-te- trahydropyridin-4-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-fluoro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[4-(propan-2-yl)piperaz- in-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[4-(propan-2-yl)piperaz- in-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(4-aminopiperidin-1-yl)-2-(2-methyl-1,3-benzothiazol-6-yl)-4H-pyrido[1,- 2-a]pyrimidin-4-one, 7-(3-aminopyrrolidin-1-yl)-2-(2-methyl-1,3-benzothiazol-6-yl)-4H-pyrido[1- ,2-a]pyrimidin-4-one, 7-[(3R)-3-(dimethylamino)pyrrolidin-1-yl]-2-(2-methyl-1,3-benzothiazol-6-- yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methyl-1,3-benzothiazol-6-yl)-7-(1,2,3,6-tetrahydropyridin-4-yl)-4H-- pyrido[1,2-a]pyrimidin-4-one, 2-(8-fluoro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[4-(2-methoxyethyl)pipe- razin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methyl-1,3-benzothiazol-6-yl)-7-(1-methyl-1,2,3,6-tetrahydropyridin-- 4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[1-(2-hydroxyethyl)-1,2,3,6-tetrahydropyridin-4-yl]-2-(2-methyl-1,3-ben- zothiazol-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methyl-1,3-benzothiazol-6-yl)-7-[1-(propan-2-yl)-1,2,3,6-tetrahydrop- yridin-4-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1-cyclopropyl-1,2,3,6-tetrahydropyridin-4-yl)-2-(2-methyl-1,3-benzothi- azol-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1-ethyl-1,2,3,6-tetrahydropyridin-4-yl)-2-(2-methyl-1,3-benzothiazol-6- -yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-3,4-dimethylpiperazin-1-yl]-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin- -2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(1 S,4S)-2,5-diazabicyclo[2.2.1]hept-2-yl]-2-(4,6-dimethylpyrazolo[1,5-a]pyr- azin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(1 S,4S)-5-methyl-2,5-diazabicyclo[2.2.1]hept-2-yl]-4H-pyrido[1,2-a]pyrimidi- n-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(1 S,4S)-5-ethyl-2,5-diazabicyclo[2.2.1]hept-2-yl]-4H-pyrido[1,2-a]pyrimidin- -4-one, 7-(4-cyclopropylpiperazin-1-yl)-2-(8-fluoro-2-methylimidazo[1,2-a]- pyridin-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-- a]pyrimidin-4-one, 2-(2-methyl-1,3-benzothiazol-6-yl)-7-(piperidin-4-yl)-4H-pyrido[1,2-a]pyr- imidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[4-(pyrrolidin-1-yl)piperid- in-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1,4'-bipiperidin-1'-yl)-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-4H- -pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[4-(4-methylpiperazin-1-yl)- piperidin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[4-(morpholin-4-yl)piperidi- n-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-6-yl)-7-(1,2,3,6-tetrahydropyridin-4-yl)- -4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-6-yl)-7-(1-methyl-1,2,3,6-tetrahydropyri- din-4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1-ethyl-1,2,3,6-tetrahydropyridin-4-yl)-2-(2-methylimidazo[1,2-a]pyrid- in-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[4-(dimethylamino)piperidin-1-yl]-2-(2-methylimidazo[1,2-a]pyridin-6-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-6-yl)-7-[4-(pyrrolidin-1-yl)piperidin-1-- yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-6-yl)-7-(piperidin-4-yl)-4H-pyrido[1,2-a- ]pyrimidin-4-one, 2-(2-methyl-1,3-benzothiazol-6-yl)-7-(1-methylpiperidin-4-yl)-4H-pyrido[1- ,2-a]pyrimidin-4-one, 7-(4-methylpiperazin-1-yl)-2-(6-methylpyrazolo[1,5-a]pyrazin-2-yl)-4H-pyr- ido[1,2-a]pyrimidin-4-one, 7-[(3 S)-3-methylpiperazin-1-yl]-2-(6-methylpyrazolo[1,5-a]pyrazin-2-yl)-4H-pyr- ido[1,2-a]pyrimidin-4-one, 7-[(3R,5 S)-3,5-dimethylpiperazin-1-yl]-2-(6-methylpyrazolo[1, 5-a]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(1-methyl-1H-indazol-5-yl)-7-(1,2,3,6-tetrahydropyridin-4-yl)-4H-pyrido- [1,2-a]pyrimidin-4-one, 2-[6-(dimethylamino)pyridin-3-yl]-7-(1,2,3,6-tetrahydropyridin-4-yl)-4H-p- yrido[1,2-a]pyrimidin-4-one, 7-[4-(diethylamino)piperidin-1-yl]-2-(2-methylimidazo[1,2-a]pyridin-6-yl)- -4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-6-yl)-7-(1-methylpiperidin-4-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 2-(1-methyl-1H-indazol-5-yl)-7-(1-methyl-1,2,3,6-tetrahydropyridin-4-yl)-- 4H-pyrido[1,2-a]pyrimidin-4-one, 2-[6-(dimethylamino)pyridin-3-yl]-7-(1-methyl-1,2,3,6-tetrahydropyridin-4- -yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[4-(diethylamino)piperidin-1-yl]-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-- 2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(piperidin-4-yl)-4H-pyrido[- 1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-methylpiperidin-4-yl)-4H- -pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-ethylpiperidin-4-yl)-4H-- pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-(4-methylpiperazin- -1-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(8aR)-hexahydropyrrolo[1,2- -a]pyrazin-2(1H)-yl]-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[4-(dimethylamino)piperidin-1-yl]-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin- -2-yl)-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1-ethyl-1,2,3,6-tetrahydropyridin-4-yl)-2-(1-methyl-1H-indazol-5-yl)-4- H-pyrido[1,2-a]pyrimidin-4-one, 2-(1-methyl-1H-indazol-5-yl)-7-(1-propyl-1,2,3,6-tetrahydropyridin-4-yl)-- 4H-pyrido[1,2-a]pyrimidin-4-one, 2-[6-(dimethylamino)pyridin-3-yl]-7-(piperidin-4-yl)-4H-pyrido[1,2-a]pyri- midin-4-one, 7-(4-ethylpiperazin-1-yl)-2-(6-methylpyrazolo[1,5-a]pyrazin-2-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 7-[(8aR)-hexahydropyrrolo[1,2-a]pyrazin-2(1H)-yl]-2-(6-methylpyrazolo[1,5- -a]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[4-(dimethylamino)piperidin-1-yl]-2-(6-methylpyrazolo[1,5-a]pyrazin-2-y- l)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[4-(2-hydroxyethyl)piperazin-1-yl]-2-(6-methylpyrazolo[1,5-a]pyrazin-2-- yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-6-yl)-7-(1-propylpiperidin-4-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 7-[1-(2-hydroxyethyl)-1,2,3,6-tetrahydropyridin-4-yl]-2-(1-methyl-1H-inda- zol-5-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-3-methylpiperazin-1-yl]-2-(6-methylpyrazolo[1,5-a]pyrazin-2-yl)-4- H-pyrido[1,2-a]pyrimidin-4-one, 2-(6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1,2,3,6-tetrahydropyridin-4-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methyl-2H-indazol-5-yl)-7-(1,2,3,6-tetrahydropyridin-4-yl)-4H-pyrido- [1,2-a]pyrimidin-4-one, 2-(1-methyl-1H-indazol-5-yl)-7-(1-methylpiperidin-4-yl)-4H-pyrido[1,2-a]p- yrimidin-4-one, 2-(2-methyl-2H-indazol-5-yl)-7-(1-methyl-1,2,3,6-tetrahydropyridin-4-yl)-- 4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1-ethyl-1,2,3,6-tetrahydropyridin-4-yl)-2-(2-methyl-2H-indazol-5-yl)-4- H-pyrido[1,2-a]pyrimidin-4-one, 7-(1-ethylpiperidin-4-yl)-2-(2-methylimidazo[1,2-a]pyridin-6-yl)-4H-pyrid- o[1,2-a]pyrimidin-4-one, 2-(1,3-dimethylpyrrolo[1,2-a]pyrazin-7-yl)-7-[1-(propan-2-yl)-1,2,3,6-tet- rahydropyridin-4-yl]-4H-pyrazino[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-(1,2,3,6-tetrahydr- opyridin-4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1, 5-a]pyrazin-2-yl)-9-methyl-7-(1-methyl-1,2,3,6-tetrahydropyridin-4-yl)-4H- -pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-ethyl-1,2,3,6-tetrahydro- pyridin-4-yl)-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1-cyclopropyl-1,2,3,6-tetrahydropyridin-4-yl)-2-(4,6-dimethylpyrazolo[- 1,5-a]pyrazin-2-yl)-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-methyl-1,2, 3,6-tetrahydropyridin-4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1-ethyl-1,2,3,6-tetrahydropyridin-4-yl)-2-(6-methylpyrazolo[1,5-a]pyra- zin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(5,7-dimethylfuro[2,3-c]pyridin-2-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-- a]pyrimidin-4-one, 2-(5,7-dimethylfuro[2,3-c]pyridin-2-yl)-7-(4-methylpiperazin-1-yl)-4H-pyr- ido[1,2-a]pyrimidin-4-one, 2-(5,7-dimethylfuro[2,3-c]pyridin-2-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(1-methyl-1H-indazol-5-yl)-7-(4-methylpiperazin-1-yl)-4H-pyrido[1,2-a]p- yrimidin-4-one, 2-(1-methyl-1H-indazol-5-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyrimidin- -4-one, 7-[4-(dimethylamino)piperidin-1-yl]-2-(1-methyl-1H-indazol-5-yl)-4- H-pyrido[1,2-a]pyrimidin-4-one, 7-(4-methyl-1,4-diazepan-1-yl)-2-(1-methyl-1H-indazol-5-yl)-4H-pyrido[1,2- -a]pyrimidin-4-one, 7-(1-ethyl-1,2,3,6-tetrahydropyridin-4-yl)-2-(2-methyl-1,3-benzoxazol-6-y- l)-4H-pyrimido[1,2-b]pyridazin-4-one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(4-ethylpiperazin-1-yl)- -4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3R)-4-ethyl-3-methylp- iperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3 S)-4-ethyl-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3R)-3-methyl-4-(propa- n-2-yl)piperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3 S)-3-methyl-4-(propan-2-yl)piperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-on- e, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(4-ethylpiperazin-1-yl)-9- -methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-[(3R)-3-methylpipe- razin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-3,4-dimethylpiperazin-1-yl]-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin- -2-yl)-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3R)-4-ethyl-3-methylpiper- azin-1-yl]-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(octahydro-5H-pyrrolo[3,2-c- ]pyridin-5-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(piperidin-4-yl)-4H-pyr- ido[1,2-a]pyrimidin-4-one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(1-methylpiperidin-4-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(1-ethylpiperidin-4-yl)- -4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[1-(propan-2-yl)piperid- in-4-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1, 5-a]pyrazin-2-yl)-9-methyl-7-(4-methyl-1,4-diazepan-1-yl)-4H-pyrido[1,2-a- ]pyrimidin-4-one, 2-(5,7-dimethylfuro[2,3-c]pyridin-2-yl)-7-[(3R,5 S)-3,5-dimethylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[4-(dimethylamino)piperidin-1-yl]-2-(5,7-dimethylfuro[2,3-c]pyridin-2-y- l)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(5,7-dimethylfuro[2,3-c]pyridin-2-yl)-7-[4-(2-hydroxyethyl)piperazin-1-- yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[1-(2-hydroxyethyl)piperidi- n-4-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[4-(2-hydroxyethyl)piperazi- n-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3R)-4-(2-hydroxyethyl)-3-- methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3 S)-4-(2-methoxyethyl)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4- -one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-{(3 S)-4-[2-(2-hydroxyethoxy)ethyl]-3-methylpiperazin-1-yl}-4H-pyrido[1,2-a]p- yrimidin-4-one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3 S)-4-cyclopropyl-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3 S)-4-cyclobutyl-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-chloro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3 S)-4-(2-hydroxyethyl)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4- -one, 2-(8-fluoro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3 S)-4-(2-methoxyethyl)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4- -one, 2-(8-fluoro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3 S)-4-(2-hydroxyethyl)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4- -one, 2-(8-fluoro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-{(3 S)-4-[2-(2-hydroxyethoxy)ethyl]-3-methylpiperazin-1-yl}-4H-pyrido[1,2-a]p- yrimidin-4-one, 2-(8-fluoro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3 S)-3-methyl-4-(propan-2-yl)piperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-on- e, 7-[(3 S)-4-cyclopropyl-3-methylpiperazin-1-yl]-2-(8-fluoro-2-methylimid- azo[1,2-a]pyridin-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3 S)-4-cyclobutyl-3-methylpiperazin-1-yl]-2-(8-fluoro-2-methylimidazo[1,2-a- ]pyridin-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(3,3-dimethylpiperazin-1-yl)-2-(4,6-dimethylpyrazolo[1, 5-a]pyrazin-2-yl)-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(1-methyl-1H-indazol-5-yl)-7-[(3R)-3-methylpiperazin-1-yl]-4H-pyrido[1,- 2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(piperazin-1-yl)-4H-pyr- ido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(4-methylpiperazin-1-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(4-ethylpiperazin-1-yl)- -4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[4-(2-hydroxyethyl)pipe- razin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[4-(dimethylamino)piperidin-1-yl]-2-(4-ethyl-6-methylpyrazolo[1,5-a]pyr- azin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[4-(diethylamino)piperidin-1-yl]-2-(4-ethyl-6-methylpyrazolo[1,5-a]pyra- zin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R,5 S)-3,5-dimethylpiperazin-1-yl]-2-(1-methyl-1H-indazol-5-yl)-4H-pyrido[1,2- -a]pyrimidin-4-one, 2-(1-methyl-1H-indazol-5-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-6-yl)-7-[1-(propan-2-yl)piperidin-4-yl]-- 4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-7-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a- ]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-7-yl)-7-(piperidin-4-yl)-4H-pyrido[1,2-a- ]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-7-yl)-7-(4-methylpiperazin-1-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 7-(4-ethylpiperazin-1-yl)-2-(2-methylimidazo[1,2-a]pyridin-7-yl)-4H-pyrid- o[1,2-a]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-7-yl)-7-(1-methylpiperidin-4-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 7-(1-ethylpiperidin-4-yl)-2-(2-methylimidazo[1,2-a]pyridin-7-yl)-4H-pyrid- o[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R,5 S)-3,5-dimethylpiperazin-1-yl]-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl- )-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3 S)-3,4-dimethylpiperazin-1-yl]-2-(4,6-dimethylpyrazolo[1, 5-a]pyrazin-2-yl)-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-[(3R,5 S)-3,4,5-trimethylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-6-yl)-7-[1-(propan-2-yl)-1,2,3,6-tetrahy- dropyridin-4-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-{4-[(dimethylamino)methyl]piperidin-1-yl}-2-(4,6-dimethylpyrazolo[1,5-a- ]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[4-(pyrrolidin-1-ylmethyl)p- iperidin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[4-(piperidin-1-ylmethyl)pi- peridin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[1-(2-hydroxyethyl)piperidin-4-yl]-2-(2-methylimidazo[1,2-a]pyridin-6-y- l)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[1-(2-hydroxyethyl)-1,2,3,6-tetrahydropyridin-4-yl]-2-(2-methylimidazo[- 1,2-a]pyridin-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methyl-2H-indazol-5-yl)-7-(1-methylpiperidin-4-yl)-4H-pyrido[1,2-a]p- yrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-{4-[(2-hydroxyethyl)(methyl- )amino]piperidin-1-yl}-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-[4-(propylamino)pi- peridin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(4-amino-4-methylpiperidin-1-yl)-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-- 2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[4-(ethylamino)piperidin-1-- yl]-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 7-{4-[bis(2-hydroxyethyl)amino]piperidin-1-yl}-2-(4,6-dimethylpyrazolo[1, 5-a]pyrazin-2-yl)-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[1-(oxetan-3-yl)piperidin-4- -yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(5,7-dimethylfuro[2,3-c]pyridin-2-yl)-7-(4-ethylpiperazin-1-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-methyloctahydro-5H-pyrro- lo[3,2-c]pyridin-5-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(1-methyl-1H-indazol-5-yl)-7-(piperidin-4-yl)-4H-pyrido[1,2-a]pyrimidin- -4-one, 7-(1-ethylpiperidin-4-yl)-2-(1-methyl-1H-indazol-5-yl)-4H-pyrido[1- ,2-a]pyrimidin-4-one, 7-[1-(2-hydroxyethyl)piperidin-4-yl]-2-(1-methyl-1H-indazol-5-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 2-(2-methyl-2H-indazol-5-yl)-7-(piperidin-4-yl)-4H-pyrido[1,2-a]pyrimidin- -4-one, 2-(2, 8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-(piperidin-4-yl)-4H-pyrido[1,2-a]- pyrimidin-4-one, 2-(2-methyl-2H-indazol-5-yl)-7-[1-(propan-2-yl)piperidin-4-yl]-4H-pyrido[- 1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-{4-[(2-hydroxyethyl)amino]p- iperidin-1-yl}-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-[4-(methylamino)pi- peridin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-[4-(propan-2-ylami- no)piperidin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1-ethylpiperidin-4-yl)-2-(2-methyl-2H-indazol-5-yl)-4H-pyrido[1,2-a]py- rimidin-4-one, 7-[1-(2-hydroxyethyl)piperidin-4-yl]-2-(2-methyl-2H-indazol-5-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 2-(2,8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-(1-methylpiperidin-4-yl)-4H-- pyrido[1,2-a]pyrimidin-4-one, 2-(2, 8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-(1-ethylpiperidin-4-yl)-4H-pyrido- [1,2-a]pyrimidin-4-one, 2-(2, 8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-[1-(propan-2-yl)piperidin-4-yl]-4- H-pyrido[1,2-a]pyrimidin-4-one, 2-(2, 8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-[1-(2-hydroxyethyl)piperidin-4-yl- ]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(4-propylpiperazin-1-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[4-(propan-2-yl)piperaz- in-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(4-cyclopropylpiperazin-1-yl)-2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin- -2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(4-cyclobutylpiperazin-1-yl)-2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-- 2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[4-(oxetan-3-yl)piperaz- in-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-ethyloctahydro-5H-pyrrol o[3,2-c]pyridin-5-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[1-(2-hydroxyethyl)octahydr- o-5H-pyrrolo[3,2-c]pyridin-5-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-methoxy-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(4-methylpiperazin-1-- yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-hydroxy-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(4-methylpiperazin-1-- yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-3,4-dimethylpiperazin-1-yl]-2-(4-ethyl-6-methylpyrazolo[1,5-a]pyr- azin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-4-ethyl-3-methylpiperazin-1-yl]-2-(4-ethyl-6-methylpyrazolo[1,5-a- ]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3R)-3-methyl-4-propyl- piperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3R)-4-(2-hydroxyethyl- )-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R,5 S)-3,5-dimethylpiperazin-1-yl]-2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-- 2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[4-(pyrrolidin-1-yl)pip- eridin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(4-methyl-1,4-diazepan-- 1-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(piperazin-1-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3R)-3-methylpiperazin-- 1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[1-(propan-2-yl)piperidin-4- -yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1-cyclopropylpiperidin-4-yl)-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-y- l)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1-cyclobutylpiperidin-4-yl)-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3R)-3-methyl-4-(propa- n-2-yl)piperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-4-cyclopropyl-3-methylpiperazin-1-yl]-2-(4-ethyl-6-methylpyrazolo- [1, 5-a]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-4-cyclobutyl-3-methylpiperazin-1-yl]-2-(4-ethyl-6-methylpyrazolo[- 1,5-a]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3R)-3-methyl-4-(oxeta- n-3-yl)piperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[4-(2-hydroxyethyl)piper- azin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(4-cyclobutylpiperazin-1-yl)-2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6- -yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3R)-4-(2-hydroxyethyl)- -3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-4-cyclobutyl-3-methylpiperazin-1-yl]-2-(8-ethyl-2-methylimidazo[1- ,2-a]pyridin-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3 S)-4-(2-hydroxyethyl)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4- -one, 7-[(3 S)-4-cyclobutyl-3-methylpiperazin-1-yl]-2-(8-ethyl-2-methylimidazo[1,2-a]- pyridin-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(piperidin-4-yl)-4H-pyr- ido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-methylpiperidin-4-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-ethylpiperidin-4-yl)- -4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[1-(2-hydroxyethyl)pipe- ridin-4-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-propylpiperidin-4-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3R)-3-methylpiperazin- -1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[1-(2-fluoroethyl)piperidin- -4-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[1-(3-fluoropropyl)piperidi- n-4-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[4-(2-fluoroethyl)piper- azin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[4-(3-fluoropropyl)pipe- razin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3R)-4-(2-fluoroethyl)- -3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3R)-4-(3-fluoropropyl- )-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[1-(2-fluoroethyl)piper- idin-4-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[1-(3-fluoropropyl)pipe- ridin-4-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-{(3R)-4-[2-(2-hydroxyethoxy- )ethyl]-3-methylpiperazin-1-yl}-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-(piperidin-4-yl)-4- H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-(1-methylpiperidin- -4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3R)-4-(2-hydroxyethyl)-3-- methylpiperazin-1-yl]-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-[8-(hydroxymethyl)-2-methylimidazo[1,2-a]pyridin-6-yl]-7-(piperazin-1-y- l)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R,5 S)-3,5-dimethylpiperazin-1-yl]-2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6- -yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(4-methyl-1,4-diazepan-1- -yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-[8-(hydroxymethyl)-2-methylimidazo[1,2-a]pyridin-6-yl]-7-(4-methylpiper- azin-1-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(4-ethylpiperazin-1-yl)-2-[8-(hydroxymethyl)-2-methylimidazo[1,2-a]pyri- din-6-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[1-(propan-2-yl)piperid- in-4-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1-cyclopropylpiperidin-4-yl)-2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin- -2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1-cyclobutylpiperidin-4-yl)-2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-- 2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[1-(oxetan-3-yl)piperid- in-4-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-cyclopropyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(piperazin-1-yl)-- 4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-cyclopropyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(4-methylpiperazi- n-1-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-cyclopropyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(4-ethylpiperazin- -1-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-cyclopropyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[4-(2-hydroxyethy- l)piperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-propylpiperidin-4-yl)-4H- -pyrido[1,2-a]pyrimidin-4-one, 2-[4-(dimethylamino)-6-methylpyrazolo[1,5-a]pyrazin-2-yl]-7-(piperazin-1-- yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methyl-1H-benzimidazol-6-yl)-7-(4-methylpiperazin-1-yl)-4H-pyrido[1,- 2-a]pyrimidin-4-one, 7-(4-ethylpiperazin-1-yl)-2-(2-methyl-1H-benzimidazol-6-yl)-4H-pyrido[1,2- -a]pyrimidin-4-one, 7-[1-(2,2-dimethyl-1,3-dioxan-5-yl)piperidin-4-yl]-2-(4-ethyl-6-methylpyr- azolo[1,5-a]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[1-(1,3-dihydroxypropan-2-yl)piperidin-4-yl]-2-(4-ethyl-6-methylpyrazol- o[1, 5-a]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R,5 S)-3,5-dimethylpiperazin-1-yl]-2-(1,3-dimethylpyrrolo[1,2-a]pyrazin-7-yl)- -4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(piperidin-4-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(1-methylpiperidin-4-yl)- -4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(1-ethylpiperidin-4-yl)-- 4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[1-(2-hydroxyethyl)piper- idin-4-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-3,4-dimethylpiperazin-1-yl]-2-(8-ethyl-2-methylimidazo[1,2-a]pyri- din-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3R)-4-ethyl-3-methylpi- perazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-ethylpiperidin-4-yl)-9-m- ethyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[1-(2-hydroxyethyl)piperidi- n-4-yl]-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1-cyclobutylpiperidin-4-yl)-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl- )-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 9-methyl-2-(2-methyl-2H-indazol-5-yl)-7-(1-methylpiperidin-4-yl)-4H-pyrid- o[1,2-a]pyrimidin-4-one, 7-[4-(dimethylamino)-4-methylpiperidin-1-yl]-2-(4,6-dimethylpyrazolo[1,5-- a]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[4-(ethylamino)-4-methylpip- eridin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[4-methyl-4-(propylamino)pi- peridin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-{4-[(2-hydroxyethyl)amino]-- 4-methylpiperidin-1-yl}-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1-cyclobutylpiperidin-4-yl)-9-methyl-2-(2-methyl-2H-indazol-5-yl)-4H-p- yrido[1,2-a]pyrimidin-4-one, 7-[1-(2-hydroxyethyl)piperidin-4-yl]-9-methyl-2-(2-methyl-2H-indazol-5-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-(1-propylpiperidin- -4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(1,3-dimethylpyrrolo[1,2-a]pyrazin-7-yl)-7-[(3R)-3-methylpiperazin-1-yl- ]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-cyclopropyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(piperazin-1-yl)-4- H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-cyclopropyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3R)-3-methylpipe- razin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-cyclopropyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-cyclopropyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3R,5 S)-3, 5-dimethylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1-cyclopropylpiperidin-4-yl)-9-methyl-2-(2-methyl-2H-indazol-5-yl)-4H-- pyrido[1,2-a]pyrimidin-4-one, 7-(1-ethylpiperidin-4-yl)-9-methyl-2-(2-methyl-2H-indazol-5-yl)-4H-pyrido- [1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-(piperazin-1-yl)-4- H-pyrido[1,2-a]pyrimidin-4-one, 9-methyl-2-(2-methyl-2H-indazol-5-yl)-7-(piperidin-4-yl)-4H-pyrido[1,2-a]- pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(1-methylpiperidin-4-yl)ox- y]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(6-methyl-4-propylpyrazolo[1,5-a]pyrazin-2-yl)-7-(piperazin-1-yl)-4H-py- rido[1,2-a]pyrimidin-4-one, 7-(4-methylpiperazin-1-yl)-2-(6-methyl-4-propylpyrazolo[1,5-a]pyrazin-2-y- l)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(4-ethylpiperazin-1-yl)-2-(6-methyl-4-propylpyrazolo[1,5-a]pyrazin-2-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[4-(2-hydroxyethyl)piperazin-1-yl]-2-(6-methyl-4-propylpyrazolo[1,5-a]p- yrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-3-methylpiperazin-1-yl]-2-(6-methyl-4-propylpyrazolo[1,5-a]pyrazi- n-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3 S)-3-methylpiperazin-1-yl]-2-(6-methyl-4-propylpyrazolo[1,5-a]pyrazin-2-y- l)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R,5 S)-3,5-dimethylpiperazin-1-yl]-2-(6-methyl-4-propylpyrazolo[1,5-a]pyrazin- -2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(1,3-dimethylpyrrolo[1,2-a]pyrazin-7-yl)-7-[(3R)-3-methyl-4-(propan-2-y- l)piperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(4-amino-4-methylpiperidin-1-yl)-2-(1,3-dimethylpyrrolo[1,2-a]pyrazin-7- -yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3 S)-3-ethylpiperazin-1-yl]-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-[2-methyl-8-(trifluoromethyl)imidazo[1,2-a]pyridin-6-yl]-7-(piperazin-1- -yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-3-methylpiperazin-1-yl]-2-[2-methyl-8-(trifluoromethyl)imidazo[1,- 2-a]pyridin-6-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3 S)-3-methylpiperazin-1-yl]-2-[2-methyl-8-(trifluoromethyl)imidazo[1,2-a]p- yridin-6-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R,5 S)-3,5-dimethylpiperazin-1-yl]-2-[2-methyl-8-(trifluoromethyl)imidazo[1,2- -a]pyridin-6-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(4-amino-4-methylpiperidin-1-yl)-2-(4-ethyl-6-methylpyrazolo[1,5-a]pyra- zin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2,7-dimethyl-2H-indazol-5-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyrim- idin-4-one, 2-(2,7-dimethyl-2H-indazol-5-yl)-7-(piperidin-4-yl)-4H-pyrido[1,2-a]pyrim- idin-4-one, 2-(2,7-dimethyl-2H-indazol-5-yl)-7-[(3R)-3-methylpiperazin-1-yl]-4H-pyrid- o[1,2-a]pyrimidin-4-one, 7-(3-aminopropyl)-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-4H-pyrido[1- ,2-a]pyrimidin-4-one, 2-(1,3-dimethylpyrrolo[1,2-a]pyrazin-7-yl)-7-(1,2,3,6-tetrahydropyridin-4- -yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(2,2,6,6-tetramethyl-1,2,3,- 6-tetrahydropyridin-4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(2,2,6,6-tetramethyl-1,- 2,3,6-tetrahydropyridin-4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3 aR,6aS)-hexahydropyrrolo[3,4-c]pyrrol-2(1H)-yl]-4H-pyrido[1,2-a]pyrimidin- -4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3 aR,6aS)-hexahydropyrrolo[3,4-c]pyrrol-2(1H)-yl]-4H-pyrido[1,2-a]pyrimidin- -4-one, 7-[(3R,5 S)-3,5-dimethylpiperazin-1-yl]-2-(1-ethyl-3-methylpyrrolo[1,2-a]pyrazin-7- -yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1,4-diazepan-1-yl)-2-(1-ethyl-3-methylpyrrolo[1,2-a]pyrazin-7-yl)-4H-p- yrido[1,2-a]pyrimidin-4-one, 2-(2,7-dimethyl-2H-indazol-5-yl)-7[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2,7-dimethyl-2H-indazol-5-yl)-7-[(3 S)-3,4-dimethylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2,7-dimethyl-2H-indazol-5-yl)-7-(1-methylpiperidin-4-yl)-4H-pyrido[1,2- -a]pyrimidin-4-one, 2-(2,7-dimethyl-2H-indazol-5-yl)-7-(1-ethylpiperidin-4-yl)-4H-pyrido[1,2-- a]pyrimidin-4-one, 9-methyl-2-(2-methyl-2H-indazol-5-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]- pyrimidin-4-one, 9-methyl-2-(2-methyl-2H-indazol-5-yl)-7-[(3R)-3-methylpiperazin-1-yl]-4H-- pyrido[1,2-a]pyrimidin-4-one, 9-methyl-2-(2-methyl-2H-indazol-5-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[3-(dimethylamino)azetidin-1-yl]-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-- 2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[3-(diethylamino)azetidin-1-yl]-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2- -yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[3-(pyrrolidin-1-yl)azetidi- n-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1,4-diazepan-1-yl)-2-(4-ethyl-6-methylpyrazolo[1, 5-a]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3 aR,6aS)-hexahydropyrrolo[3,4-c]pyrrol-2(1H)-yl]-2-(6-methyl-4-propylpyraz- olo[1,5-a]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(6-methyl-4-propylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1,2,3,6-tetrahydropyr- idin-4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1,2,3,6-tetrahydropyri- din-4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3 S)-3-(aminomethyl)pyrrolidin-1-yl]-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-- 2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[3-(piperidin-1-yl)azetidin- -1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(6-methyl-4-propylpyrazolo[1,5-a]pyrazin-2-yl)-7-(piperidin-4-yl)-4H-py- rido[1,2-a]pyrimidin-4-one, 7-(2,7-diazaspiro[4.4]non-2-yl)-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-y- l)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2,7-dimethyl-2H-indazol-5-yl)-7-(4-methylpiperazin-1-yl)-4H-pyrido[1,2- -a]pyrimidin-4-one, 7-{(3 S)-3-[(dimethylamino)methyl]pyrrolidin-1-yl}-2-(4,6-dimethylpyrazolo[1,5-- a]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-(piperidin-4-y- l)-4H-pyrido[1,2-a]pyrimidin-4-one, 9-methyl-2-(1-methyl-1H-indazol-5-yl)-7-(piperidin-4-yl)-4H-pyrido[1,2-a]- pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-(1,2,3,6-tetra- hydropyridin-4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-(1-methylpiper- idin-4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(1,7-dimethyl-1H-indazol-5-yl)-7-(piperidin-4-yl)-4H-pyrido[1,2-a]pyrim- idin-4-one, 2-(1,7-dimethyl-1H-indazol-5-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyrim- idin-4-one, 2-(1,7-dimethyl-1H-indazol-5-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-{(3 S)-3-[(diethylamino)methyl]pyrrolidin-1-yl}-2-(4,6-dimethylpyrazolo[1,5-a- ]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-{(3 S)-3-[(ethylamino)methyl]pyrrolidin-1-yl}-4H-pyrido[1,2-a]pyrimidin-4-one- , 7-{3-[(dimethylamino)methyl]azetidin-1-yl}-2-(4,6-dimethylpyrazolo[1,5-a- ]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-{3-[(diethylamino)methyl]azetidin-1-yl}-2-(4,6-dimethylpyrazolo[1, 5-a]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(1-ethyl-3-methylpyrrolo[1,2-a]pyrazin-7-yl)-7-[(8aS)-hexahydropyrrolo[- 1,2-a]pyrazin-2(1H)-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-[(3R)-3-methyl- piperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 9-methyl-2-(1-methyl-1H-indazol-5-yl)-7-(1-methylpiperidin-4-yl)-4H-pyrid- o[1,2-a]pyrimidin-4-one, 7-[(3R)-3,4-dimethylpiperazin-1-yl]-2-(4-ethyl-6-methylpyrazolo[1,5-a]pyr- azin-2-yl)-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1-ethylpiperidin-4-yl)-9-methyl-2-(1-methyl-1H-indazol-5-yl)-4H-pyrido- [1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[1-(2-hydroxyethyl)piperidin-4-yl]-9-methyl-2-(1-methyl-1H-indazol-5-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3 S)-3,4-dimethylpiperazin-1-yl]-2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-- 2-yl)-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-ethylpiperidin-4-yl)- -9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(1-cyclobutylpiperidin-4-yl)-2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-- 2-yl)-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[1-(2-hydroxyethyl)pipe- ridin-4-yl]-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(8aR)-hexahydropyrrolo[- 1,2-a]pyrazin-2(1H)-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(8aS)-hexahydropyrrolo[- 1,2-a]pyrazin-2(1H)-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-3-(aminomethyl)pyrrolidin-1-yl]-2-(4,6-dimethylpyrazolo[1,5-a]pyr- azin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(2 S,6 S)-2,6-dimethyl-1,2,3,6-tetrahydropyridin-4-yl]-4H-pyrido[1,2-a]pyrimidin- -4-one, 7-{(3R)-3-[(dimethylamino)methyl]pyrrolidin-1-yl}-2-(4,6-dimethylp- yrazolo[1, 5-a]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(2S,6S)-2,6-dimethylpiperidin-4-yl]-2-(4,6-dimethylpyrazolo[1,5-a]pyra- zin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-fluoro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[4-(2-hydroxyethyl)pipe- razin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(imidazo[1,2-a]pyridin-6-yl)-7-(4-methylpiperazin-1-yl)-4H-pyrido[1,2-a- ]pyrimidin-4-one, 2-(4-fluoro-2-methyl-1,3-benzoxazol-6-yl)-7-[(8aS)-hexahydropyrrolo[1,2-a- ]pyrazin-2(1H)-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(2,7-diazaspiro[3 0.5]non-7-yl)-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-4H-pyrido[1,2-a- ]pyrimidin-4-one, 7-(4-methylpiperazin-1-yl)-2-(2-methyl[1,2,4]triazolo[1,5-a]pyridin-6-yl)- -4H-pyrido[1,2-a]pyrimidin-4-one, 7-(4-methylpiperazin-1-yl)-2-[2-methyl-8-(trifluoromethyl)imidazo[1,2-a]p- yridin-6-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-methyl-6-[7-(4-methylpiperazin-1-yl)-4-oxo-4H-pyrido[1,2-a]pyrimidin-2-- yl]imidazo[1,2-a]pyridine-8-carbonitrile 2-(2, 8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-(4-methylpiperazin-1-yl)-4H-pyrid- o[1,2-a]pyrimidin-4-one, 7-(4,7-diazaspiro[2.5]oct-7-yl)-2-(2,8-dimethylimidazo[1,2-a]pyridin-6-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-fluoro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(1-methylpiperidin-4-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-fluoro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(4-hydroxypiperidin-4-y- l)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(8aS)-hexahydropyrrolo- [1,2-a]pyrazin-2(1H)-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(8 aR)-hexahydropyrrolo[1,2-a]pyrazin-2(1H)-yl]-4H-pyrido[1,2-a]pyrimidin-4-- one, 7-[(3R)-3-(dimethylamino)pyrrolidin-1-yl]-2-(4-ethyl-6-methylpyrazolo- [1,5-a]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3 S)-3-(dimethylamino)pyrrolidin-1-yl]-2-(4-ethyl-6-methylpyrazolo[1,5-a]py- razin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-fluoro-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(8aS)-8a-methylhexahyd- ropyrrolo[1,2-a]pyrazin-2(1H)-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(4-ethylpiperazin-1-yl)- -9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(8aS)-hexahydropyrrolo- [1,2-a]pyrazin-2(1H)-yl]-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2,8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-(4-ethylpiperazin-1-yl)-4H-p- yrido[1,2-a]pyrimidin-4-one, 2-(2,8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-[(8aS)-hexahydropyrrolo[1,2-- a]pyrazin-2(1H)-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2,8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-(8a-methylhexahydropyrrolo[1- ,2-a]pyrazin-2(1H)-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-3-(dimethylamino)pyrrolidin-1-yl]-2-(4-ethyl-6-methylpyrazolo[1,5- -a]pyrazin-2-yl)-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-{[2-(morpholin-4-yl)eth- yl]amino}-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-3-(dimethylamino)pyrrolidin-1-yl]-2-(2,8-dimethylimidazo[1,2-a]py- ridin-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3 S)-3-(dimethylamino)pyrrolidin-1-yl]-2-(2, 8-dimethylimidazo[1,2-a]pyridin-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, or 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3aR,6aS)-5-methylhexahydr- opyrrolo[3,4-c]pyrrol-2(1H)-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, or a salt, isotopologue, stereoisomer, racemate, enantiomer, diastereomer or tautomer thereof. 10. The compound of claim 1, wherein R.sub.1 is heterocyclyl selected from azetidinyl, tetrahydrofuranyl, pyrrolidinyl, piperidinyl, piperazinyl, 1,4-diazepanyl, 1,2,5,6-tetrahydropyridinyl, 1,2,3,6-tetrahydropyridinyl, hexahydropyrrolo[3,4-b]pyrrol-(1H)-yl, (3aS,6aS)-hexahydropyrrolo[3,4-b]pyrrol-(1H)-yl, (3aR,6aR)-hexahydropyrrolo[3,4-b]pyrrol-(1H)-yl, hexahydropyrrolo[3,4-b]pyrrol-(2H)-yl, (3aS,6aS)-hexahydropyrrolo[3,4-b]pyrrol-(2H)-yl, hexahydropyrrolo[3,4-c]pyrrol-(1H)-yl, (3aR,6aS)-hexahydropyrrolo[3,4-c]pyrrol-(1H)-yl, octahydro-5H-pyrrolo[3,2-c]pyridinyl, octahydro-6H-pyrrolo[3,4-b]pyridinyl, (4aR,7aR)-octahydro-6H-pyrrolo[3,4-b]pyridinyl, (4aS,7aS)-octahydro-6H-pyrrolo[3,4-b]pyridinyl, hexahydropyrrolo[1,2-a]pyrazin-(2H)-one, hexahydropyrrolo[1,2-a]pyrazin-(1H)-yl, (7R,8aS)-hexahydropyrrolo[1,2-a]pyrazin-(1H)-yl, (8aS)-hexahydropyrrolo[1,2-a]pyrazin-(1H)-yl, (8aR)-hexahydropyrrolo[1,2-a]pyrazin-(1H)-yl, (8aS)-octahydropyrrolo[1,2-a]pyrazin-(1H)-yl, (8aR)-octahydropyrrolo[1,2-a]pyrazin-(1H)-yl, octahydro-2H-pyrido[1,2-a]pyrazinyl, 3-azabicyclo[3.1.0]hexyl, (1R,5S)-3-azabicyclo[3.1.0]hexyl, 8-azabicyclo[3.2.1]octyl, (1R,5S)-8-azabicyclo[3.2.1]octyl, 8-azabicyclo[3.2.1]oct-2-enyl, (1R,5S)-8-azabicyclo[3.2.1]oct-2-enyl, 9-azabicyclo[3.3.1]nonyl, (1R,5S)-9-azabicyclo[3.3.1]nonyl, 2,5-diazabicyclo[2.2.1]heptyl, (1S,4S)-2,5-diazabicyclo[2.2.1]heptyl, 2,5-diazabicyclo[2.2.2]octyl, 3,8-diazabicyclo[3.2.1]octyl, (1R,5S)-3,8-diazabicyclo[3.2.1]octyl, 1,4-diazabicyclo[3.2.2]nonyl, azaspiro[3.3]heptyl, 2,6-diazaspiro[3.3]heptyl, 2,7-diazaspiro[3.5]nonyl, 5,8-diazaspiro[3.5]nonyl, 2,7-diazaspiro[4.4]nonyl and 6,9-diazaspiro[4.5]decyl; wherein, each instance of heterocyclyl is optionally substituted one, two or three R.sub.3 substituents and optionally, with one additional R.sub.4 substituent. 11. The compound of claim 1, wherein R.sub.2 is heteroaryl selected from furo[3,2-b]pyridinyl, furo[3,2-c]pyridinyl, furo[2,3-c]pyridinyl, thieno[3,2-c]pyridinyl, thieno[2,3-d]pyrimidinyl, 1H-pyrrolo[2,3-b]pyridinyl, 1H-pyrrolo[2,3-c]pyridinyl, pyrrolo[1,2-a]pyrimidinyl, pyrrolo[1,2-a]pyrazinyl, pyrrolo[1,2-b]pyridazinyl, pyrazolo[1,5-a]pyridinyl, pyrazolo[1,5-a]pyrazinyl, imidazo[1,2-a]pyridinyl, imidazo[1,2-a]pyrimidinyl, imidazo[1,2-c]pyrimidinyl, imidazo[1,2-b]pyridazinyl, imidazo[1,2-a]pyrazinyl, imidazo[2,1-b][1,3]thiazolyl, imidazo[2,1-b][1,3,4]thiadiazolyl, [1,3]oxazolo[4,5-b]pyridinyl and quinoxalinyl; wherein, each instance of heteroaryl is optionally substituted with one, two or three R.sub.6 substituents and optionally, with one additional R.sub.7 substituent. 12. The compound of claim 9, wherein the compound is selected from the group consisting of: 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(piperidin-4-yl)-4H-pyrido[- 1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-methylpiperidin-4-yl)-4H- -pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-ethylpiperidin-4-yl)-4H-- pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[1-(propan-2-yl)piperidin-4- -yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1, 5-a]pyrazin-2-yl)-7-(piperidin-4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-methylpiperidin-4-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-ethylpiperidin-4-yl)- -4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-propylpiperidin-4-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-(piperidin-4-yl)-4- H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-(1-methylpiperidin- -4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[1-(propan-2-yl)piperid- in-4-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-propylpiperidin-4-yl)-4H- -pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-(1-propylpiperidin- -4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(6-methyl-4-propylpyrazolo[1,5-a]pyrazin-2-yl)-7-(piperidin-4-yl)-4H-py- rido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-(piperidin-4-y- l)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-(1-methylpiper- idin-4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-ethylpiperidin-4-yl)- -9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-ethylpiperidin-4-yl)-9-m- ethyl-4H-pyrido[1,2-a]pyrimidin-4-one, or 7-[(2S,6S)-2,6-dimethylpiperidin-4-yl]-2-(4,6-dimethylpyrazolo[1,5-a]pyra- zin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, or a salt, isotopologue, stereoisomer, racemate, enantiomer, diastereomer or tautomer thereof. 13. The compound of claim 9, wherein the compound is selected from the group consisting of: 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(piperazin-1-yl)-4H-pyrido[- 1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R,5S)-3,5-dimethylpiperazin-1-yl]-2-(4,6-dimethylpyrazolo[1,5-a]pyra- zin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(4-methylpiperazin-1-yl)-4H- -pyrido[1,2-a]pyrimidin-4-one, 7-[(3 S)-3,4-dimethylpiperazin-1-yl]-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3R,5 S)-3,4,5-trimethylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3R)-3-methylpiperazin-1-y- l]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(4-ethylpiperazin-1-yl)-4H-- pyrido[1,2-a]pyrimidin-4-one, 7-(3,3-dimethylpiperazin-1-yl)-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3R)-4-ethyl-3-methylpiper- azin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-3,4-dimethylpiperazin-1-yl]-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin- -2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(6-methylpyrazolo[1, 5-a]pyrazin-2-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(4-methylpiperazin-1-yl)-2-(6-methylpyrazolo[1,5-a]pyrazin-2-yl)-4H-pyr- ido[1,2-a]pyrimidin-4-one, 7-[(3 S)-3-methylpiperazin-1-yl]-2-(6-methylpyrazolo[1,5-a]pyrazin-2-yl)-4H-pyr- ido[1,2-a]pyrimidin-4-one, 7-[(3R,5 S)-3, 5-dimethylpiperazin-1-yl]-2-(6-methylpyrazolo[1,5-a]pyrazin-2-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-(4-methylpiperazin- -1-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(4-ethylpiperazin-1-yl)-2-(6-methylpyrazolo[1,5-a]pyrazin-2-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 7-[(3R)-3-methylpiperazin-1-yl]-2-(6-methylpyrazolo[1, 5-a]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(4-ethylpiperazin-1-yl)-9-m- ethyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-[(3R)-3-methylpipe- razin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-3,4-dimethylpiperazin-1-yl]-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin- -2-yl)-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3R)-4-ethyl-3-methylpiper- azin-1-yl]-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(3,3-dimethylpiperazin-1-yl)-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl- )-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(piperazin-1-yl)-4H-pyr- ido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(4-methylpiperazin-1-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(4-ethylpiperazin-1-yl)- -4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R,5 S)-3, 5-dimethylpiperazin-1-yl]-2-(4,6-dimethylpyrazolo[1, 5-a]pyrazin-2-yl)-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3 S)-3,4-dimethylpiperazin-1-yl]-2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl- )-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-[(3R,5 S)-3,4, 5-trimethylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(4-propylpiperazin-1-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[4-(propan-2-yl)piperaz- in-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-3,4-dimethylpiperazin-1-yl]-2-(4-ethyl-6-methylpyrazolo[1,5-a]pyr- azin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-4-ethyl-3-methylpiperazin-1-yl]-2-(4-ethyl-6-methylpyrazolo[1,5-a- ]pyrazin-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3R)-3-methyl-4-propyl- piperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R,5 S)-3, 5-dimethylpiperazin-1-yl]-2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)- -4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3R)-3-methyl-4-(propa- n-2-yl)piperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3R)-3-methylpiperazin- -1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-(piperazin-1-yl)-4- H-pyrido[1,2-a]pyrimidin-4-one, 2-(6-methyl-4-propylpyrazolo[1,5-a]pyrazin-2-yl)-7-(piperazin-1-yl)-4H-py- rido[1,2-a]pyrimidin-4-one, 7-(4-methylpiperazin-1-yl)-2-(6-methyl-4-propylpyrazolo[1,5-a]pyrazin-2-y- l)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-(4-ethylpiperazin-1-yl)-2-(6-methyl-4-propylpyrazolo[1,5-a]pyrazin-2-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-3-methylpiperazin-1-yl]-2-(6-methyl-4-propylpyrazolo[1,5-a]pyrazi- n-2-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3 S)-3-methylpiperazin-1-yl]-2-(6-methyl-4-propylpyrazolo[1,5-a]pyrazin-2-y- l)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R,5 S)-3, 5-dimethylpiperazin-1-yl]-2-(6-methyl-4-propylpyrazolo[1,5-a]pyrazin-2-yl- )-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-[(3 S)-3-ethylpiperazin-1-yl]-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-[(3R)-3-methyl- piperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-3,4-dimethylpiperazin-1-yl]-2-(4-ethyl-6-methylpyrazolo[1,5-a]pyr- azin-2-yl)-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-[(3S)-3-methyl- piperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3 S)-3,4-dimethylpiperazin-1-yl]-2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-- 2-yl)-9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, or 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(4-ethylpiperazin-1-yl)- -9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, or a salt, isotopologue, stereoisomer, racemate, enantiomer, diastereomer or tautomer thereof. 14. The compound of claim 9, wherein the compound is selected from the group consisting of: 2-(2-methylimidazo[1,2-a]pyridin-6-yl)-7-(piperidin-4-yl)-4H-pyrido[1,2-a- ]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-6-yl)-7-(1-methylpiperidin-4-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-6-yl)-7-(1-propylpiperidin-4-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 7-(1-ethylpiperidin-4-yl)-2-(2-methylimidazo[1,2-a]pyridin-6-yl)-4H-pyrid- o[1,2-a]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-6-yl)-7-[1-(propan-2-yl)piperidin-4-yl]-- 4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-7-yl)-7-(piperidin-4-yl)-4H-pyrido[1,2-a- ]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-7-yl)-7-(1-methylpiperidin-4-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 7-(1-ethylpiperidin-4-yl)-2-(2-methylimidazo[1,2-a]pyridin-7-yl)-4H-pyrid- o[1,2-a]pyrimidin-4-one, 2-(2,8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-(piperidin-4-yl)-4H-pyrido[1- ,2-a]pyrimidin-4-one, 2-(2,8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-(1-methylpiperidin-4-yl)-4H-- pyrido[1,2-a]pyrimidin-4-one, 2-(2,8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-(1-ethylpiperidin-4-yl)-4H-p- yrido[1,2-a]pyrimidin-4-one, 2-(2,8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-[1-(propan-2-yl)piperidin-4-- yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(piperidin-4-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(1-methylpiperidin-4-yl)- -4H-pyrido[1,2-a]pyrimidin-4-one, or 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(1-ethylpiperidin-4-yl)-- 4H-pyrido[1,2-a]pyrimidin-4-one, or a salt, isotopologue, stereoisomer, racemate, enantiomer, diastereomer or tautomer thereof. 15. The compound of claim 9, wherein the compound is selected from the group consisting of: 2-(imidazo[1,2-a]pyridin-7-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a]pyrimid- in-4-one, 2-(imidazo[1,2-a]pyridin-6-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-- a]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-6-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a- ]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-6-yl)-7-(4-methylpiperazin-1-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3S)-3-methylpiperazin-1-yl]-4H- -pyrido[1,2-a]pyrimidin-4-one, 7-[(3R,5 S)-3,5-dimethylpiperazin-1-yl]-2-(2-methylimidazo[1,2-a]pyridin-6-yl)-4H-- pyrido[1,2-a]pyrimidin-4-one, 2-(2,8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-(piperazin-1-yl)-4H-pyrido[1- ,2-a]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-7-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-a- ]pyrimidin-4-one, 2-(2-methylimidazo[1,2-a]pyridin-7-yl)-7-(4-methylpiperazin-1-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 7-(4-ethylpiperazin-1-yl)-2-(2-methylimidazo[1,2-a]pyridin-7-yl)-4H-pyrid- o[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(piperazin-1-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3R)-3-methylpiperazin-- 1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3 S)-3-methylpiperazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R,5S)-3,5-dimethylpiperazin-1-yl]-2-(8-ethyl-2-methylimidazo[1,2-a]p- yridin-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 7-[(3R)-3,4-dimethylpiperazin-1-yl]-2-(8-ethyl-2-methylimidazo[1,2-a]pyri- din-6-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3R)-4-ethyl-3-methylpi- perazin-1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(imidazo[1,2-a]pyridin-6-yl)-7-(4-methylpiperazin-1-yl)-4H-pyrido[1,2-a- ]pyrimidin-4-one, 2-(2,8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-(4-methylpiperazin-1-yl)-4H-- pyrido[1,2-a]pyrimidin-4-one, or 2-(2,8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-(4-ethylpiperazin-1-yl)-4H-p- yrido[1,2-a]pyrimidin-4-one, or a salt, isotopologue, stereoisomer, racemate, enantiomer, diastereomer or tautomer thereof. 16. The compound of claim 9, wherein the compound is selected from the group consisting of: 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-(1-methylpiperidin- -4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(1-ethylpiperidin-4-yl)-9-m- ethyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-(1-propylpiperidin- -4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(6-methyl-4-propylpyrazolo[1,5-a]pyrazin-2-yl)-7-(piperidin-4-yl)-4H-py- rido[1,2-a]pyrimidin-4-one, 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-(piperidin-4-y- l)-4H-pyrido[1,2-a]pyrimidin-4-one, or 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-(1-methylpiper- idin-4-yl)-4H-pyrido[1,2-a]pyrimidin-4-one, or a salt, isotopologue, stereoisomer, racemate, enantiomer, diastereomer or tautomer thereof. 17. The compound of claim 9, wherein the compound is selected from the group consisting of: 2-(2,8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-(piperazin-1-yl)-4H-pyrido[1- ,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(piperazin-1-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3R)-3-methylpiperazin-- 1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-[(3S)-3-methylpiperazin-- 1-yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(2,8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-(4-methylpiperazin-1-yl)-4H-- pyrido[1,2-a]pyrimidin-4-one, or 2-(2,8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-(4-ethylpiperazin-1-yl)-4H-p- yrido[1,2-a]pyrimidin-4-one, or a salt, isotopologue, stereoisomer, racemate, enantiomer, diastereomer or tautomer thereof. 18. The compound of claim 9, wherein the compound is selected from the group consisting of: 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(piperazin-1-yl)-4H-pyrido[- 1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(4-ethylpiperazin-1-yl)-4H-- pyrido[1,2-a]pyrimidin-4-one, 2-(6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(piperazin-1-yl)-4H-pyrido[1,2-- a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-7-(4-ethylpiperazin-1-yl)-9-m- ethyl-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(4,6-dimethylpyrazolo[1,5-a]pyrazin-2-yl)-9-methyl-7-(piperazin-1-yl)-4- H-pyrido[1,2-a]pyrimidin-4-one, or 2-(4-ethyl-6-methylpyrazolo[1,5-a]pyrazin-2-yl)-7-(4-ethylpiperazin-1-yl)- -9-methyl-4H-pyrido[1,2-a]pyrimidin-4-one, or a salt, isotopologue, stereoisomer, racemate, enantiomer, diastereomer or tautomer thereof. 19. The compound of claim 9, wherein the compound is selected from the group consisting of: 2-(2,8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-(piperidin-4-yl)-4H-pyrido[1- ,2-a]pyrimidin-4-one, 2-(2,8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-(1-methylpiperidin-4-yl)-4H-- pyrido[1,2-a]pyrimidin-4-one, 2-(2,8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-(1-ethylpiperidin-4-yl)-4H-p- yrido[1,2-a]pyrimidin-4-one, 2-(2,8-dimethylimidazo[1,2-a]pyridin-6-yl)-7-[1-(propan-2-yl)piperidin-4-- yl]-4H-pyrido[1,2-a]pyrimidin-4-one, 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(piperidin-4-yl)-4H-pyri- do[1,2-a]pyrimidin-4-one, or 2-(8-ethyl-2-methylimidazo[1,2-a]pyridin-6-yl)-7-(1-methylpiperidin-4-yl)- -4H-pyrido[1,2-a]pyrimidin-4-one, or a salt, isotopologue, stereoisomer, racemate, enantiomer, diastereomer or tautomer thereof. 20. A pharmaceutical composition comprising an effective amount of the compound of claim 1 and a pharmaceutically acceptable carrier, excipient or diluent. 21. A pharmaceutical composition comprising an effective amount of the compound of claim 9 and a pharmaceutically acceptable carrier, excipient or diluent.