Claims for Patent: 6,562,861

Summary for Patent: 6,562,861

Title:	Substituted cyclopentane and cyclopentene compounds useful as neuraminidase inhibitors
Abstract:	##STR1## Compounds I-III wherein U is CH, O, or S; Z is mono- or di-substituted carbon; R is (CH2)nCO2H, (CH2)nSO3H, (CH2)nPO3H2, (CH2)nNO2, CH(SCH3)3, esters; R1 is H, hydroxyalkyl, aminoalkyl, alkoxyalkyl; RR1 is O; n is 0-4; R2, R3 is H, hydroxyalkyl, aminoalkyl, alkoxyalkyl, haloalkyl; R4 is (CH2)nOH, (CH2)nNH2, substituted alkyl were prepd. as neuraminidase inhibitors. Thus, (1R,3R,4R,1'S)-(-)-(1'-acetylamino-2 '-ethyl)butyl-4-(aminoimino)methylaminocyclopentan-1-carboxylic acid was prepd. and tested in vitro as neuraminidase inhibitor (IC50<1.mu.M).
Inventor(s):	Babu; Yarlagadda S. (Birmingham, AL), Chand; Pooran (Birmingham, AL), Montgomery; John A. (Birmingham, AL)
Assignee:	BioCryst Pharmaceuticals, Inc. (Birmingham, AL)
Application Number:	09/555,131
Patent Claims:	1. A compound represented by the formulae: ##STR244## wherein U is CH and p is 1 Z is --C(R.sub.2)(R.sub.3), --CH--N(R.sub.2)(R.sub.3), C(R.sub.3)[(CH.sub.2).sub.n R.sub.2 ], CH--C(R.sub.3)(R.sub.8)(CH.sub.2).sub.n R.sub.2, C[(CH.sub.2).sub.n R.sub.2 ]--[CH(R.sub.3)(R.sub.8)], C[(R.sub.3)][CH(CH.sub.2).sub.n R.sub.2 (R.sub.8)]; R.sub.1 is H, (CH.sub.2).sub.n OH, (CH.sub.2).sub.n NH.sub.2, (CH.sub.2).sub.n NR.sub.10 R.sub.11, (CH.sub.2).sub.n OR.sub.11, (CH.sub.2).sub.n SR.sub.11, (CH.sub.2).sub.n halogen R.sub.9 is (CH.sub.2).sub.n CO.sub.2 H, (CH.sub.2).sub.n SO.sub.3 H, (CH.sub.2).sub.n PO.sub.3 H.sub.2, (CH.sub.2).sub.n NO.sub.2, C(SCH.sub.3).sub.3, esters thereof, or salts thereof; or R.sub.1 R.sub.9 together represent ##STR245## R.sub.2 is NHC(O)R.sub.5, NHC(S)R.sub.5, NHSO.sub.2 R.sub.5, C(O)NHR.sub.5, SO.sub.2 NHR.sub.5, CH.sub.2 S(O)R.sub.5, or CH.sub.2 SO.sub.2 R.sub.5 ; R.sub.3 and R.sub.8 individually is H, (CH.sub.2).sub.n C(O)R.sub.10, (CH.sub.2).sub.n CO.sub.2 R.sub.10, (CH.sub.2).sub.m OR.sub.10, CH(OR.sub.10)CH(R.sub.10).sub.m, C(O)N(R.sub.10).sub.m, C(O)N(OR.sub.10)R.sub.10, (CH.sub.2).sub.n N(R.sub.10).sub.m, CH(R.sub.10) when m is 2, (CH.sub.2).sub.n (R.sub.10).sub.m, CH.sub.2 CH(OR.sub.10)CH.sub.2 OR.sub.10, CH(OR.sub.10)CH(OR.sub.10)CH.sub.2 OR.sub.10, CH.sub.2 OR.sub.10, CH(OR.sub.10)CH.sub.2 NHR.sub.10, CH.sub.2 CH(OR.sub.10)CH.sub.2 NHR.sub.10, CH(OR.sub.10)CH(OR.sub.10)CH.sub.2 NHR.sub.10, C(.dbd.NR.sub.10)N(R.sub.10).sub.m, NHR.sub.10, NHC(.dbd.NR.sub.10)N(R.sub.10).sub.m, provided that at least one of R.sub.2, R.sub.3 and R.sub.8 is other than H; R.sub.4 is (CH.sub.2).sub.n OH, (CH.sub.2).sub.n OR.sub.11, (CH.sub.2).sub.n OC(O)R.sub.11, (CH.sub.2).sub.n NHC(.dbd.NR.sub.11)NHR.sub.11, (CH.sub.2).sub.n NR.sub.10 R.sub.11, (CH.sub.2).sub.n NH.sub.2, (CH.sub.2).sub.n C(.dbd.NH)(NH.sub.2), (CH.sub.2).sub.n NHC(.dbd.NR.sub.11)NH.sub.2, (CH.sub.2).sub.n NHC(.dbd.NR.sub.7)NH.sub.2, (CH.sub.2).sub.n CN, (CH.sub.2).sub.n N.sub.3, C(.dbd.NH)NH.sub.2, C(NR.sub.7)NH.sub.2, or C(NR.sub.11)NH.sub.2 ; R.sub.5 is H, lower alkyl, cyclo alkyl, halogen substituted alkyl, aryl, substituted aryl or CF.sub.3 ; R.sub.7 is H, (CH.sub.2).sub.n OH, (CH.sub.2).sub.n CN, (CH.sub.2).sub.n NH.sub.2, or (CH.sub.2).sub.n NO.sub.2 ; R.sub.10 is H, lower alkyl, lower alkylene, branched alkyl, cyclic alkyl, (CH.sub.2).sub.n aromatic, (CH.sub.2).sub.n substituted aromatic, or when m is 2 both R.sub.10 groups can also be interconnected to form an N substituted heterocyclic ring, or other 5- or 6-membered heterocyclic ring; R.sub.11 is lower alkyl, branched alkyl, (CH.sub.2).sub.m aromatic, SO.sub.2 R.sub.10, C(O)R.sub.10 or C(O)OR.sub.10 ; R.sub.12 and R.sub.13 is (CH.sub.2).sub.n OH, (CH.sub.2).sub.n NH.sub.2, (CH.sub.2).sub.n NR.sub.10 R.sub.11, (CH.sub.2).sub.n OR.sub.11, (CH.sub.2).sub.n F, (CH.sub.2).sub.n OC(O)R.sub.11, or (CH.sub.2).sub.n NHC(O)R.sub.11, and R.sub.12 can also be H; m is 1 or 2; n is 0-4; p is 0 or 1; and pharmaceutically acceptable salts thereof. 2. The compound of claim 1, wherein said lower alkyl group contains 1 to 8 carbon atoms; and said lower alkylene group contains 2 to 8 carbon atoms. 3. The compound of claim 1, wherein said lower alkyl group contains 1 to 3 carbon atoms; and said lower alkylene group contains 2 to 3 carbon atoms. 4. The compound of claim 1, wherein said alkyl group R.sub.5, R.sub.10 and R.sub.11 is selected from the group consisting of methyl, ethyl, propyl, isopropyl, t-butyl, cyclopentyl, and cyclohexyl, the aromatic group is selected from the group consisting of phenyl and alkyl substituted aromatic groups; the substituted cycloalkyl group contains 3-8 carbon atoms in the ring and are substituted with 1 or 2 alkyl groups having 1-6 carbon atoms, hydroxy group or both; and the alkylene group is selected from the group consisting of vinyl, 1-propenyl, allyl, isopropenyl, 2-methyl-2-propenyl and cyclopentenyl. 5. The compound of claim 1, wherein said salt is from acid selected from the group consisting of hydrochloric, hydrobromic, sulfuric, nitric, perchloric, fumaric, maleic, phosphoric, glycollic, lactic, salicylic, succinic, toluene-p-sulphonic, tartaric, acetic, citric, methanesulphonic, formic, benzoic, malonic, napthalene-2-sulphonic, trifluoroacetic and benzenesulphonic acids. 6. The compound of claim 1, wherein said salt is a sodium or ammonium salt. 7. A compound being selected from the group consisting of (+) 4-Azidocyclopent-2-en-1-one, (+) 3.beta.-{(1'-acetylamino'bis(ethoxycarbonyl)}methyl-4.alpha.-azidocyclopen tan-1-one, (+) 3.beta.-{1'-Acetylamino-1'-bis(ethoxycarbonyl)}methyl-4.alpha.-tert-butoxy carbonylamino-cyclopentan-1-one, (+) 2-{3.beta.-{1'-Acetylamino-1'-bis(ethoxycarbonyl)}methyl-4.alpha.-tert-but oxycarbonyl-amino-1-cyclopentylidene}-1,3-dithiane, (+) 2-{3.beta.-(1'-Acetylamino-1'-carboxy)methyl-4.alpha.-tert-butoxycarbonyla mino-1-cyclopentylidene}-1,3-dithiane, (+) 2-{3.beta.-{1'-Acetylamino-1'-{(N-methoxy-N-methyl)aminocarbonyl}methyl}-4 .alpha.-tert-butoxycarbonylamino-1-cyclopentylidene}-1,3-dithiane, (+) 2-{3.beta.-(1'-Acetylamino-1'-formyl)methyl-4.alpha.-tert-butoxycarbonylam ino-1-cyclopentylidene}-1,3-dithiane, (+) 2-{3.beta.-(1'-Acetylamino-1'-ethoxycarbonyl)methyl-4.alpha.-tert-butoxyca rbonylamino-1-cyclopentylidene}-1,3-dithiane, (+) 2-{3.beta.-(1'-Acetylamino-2'-hydroxy)ethyl-4.alpha.-tert-butoxycarbonylam ino-1-cyclopentylidene}-1,3-dithiane, (+) 2-{3.beta.-(1'-acetylamino-2'-ethoxy)ethyl-4.alpha.-(tert-butoxycarbonyl)a mino-1-cyclopentylidene}-1,3-dithiane, (+) Methyl-3.beta.-(1'-acetylamino-2'-ethoxy)ethyl-4.alpha.-(tert-butoxycarbon yl)aminocyclopentan-1-carboxylate and (+) Methyl 3.beta.-(1'-acetylamino-2'-ethoxy)ethyl-4.alpha.-aminocyclopentan-r-1-carb oxylate, (+) 3.beta.-(1'-Acetylamino-2'-ethoxy)ethyl-4.alpha.-aminocyclopentan-1-carbox ylic acid, (+) 3.beta.-(1'-Acetylamino-2'-ethoxy)ethyl-4.alpha.-{(aminoimino)methyl}amino cyclopentan-1-carboxylic acid, (+) t-3-(1'-Acetylamino-1'-di(ethoxycarbonyl)}methyl-c-4-tert-butoxycarbonylam ino-t-1-(trismethylthio)methyl}cyclopentan-r-1-ol, (+) t-3-[1'-Acetylamino-1'-carboxy)}methyl-c-4-tert-butoxycarbonylamino-t-1-[( tris methylthio)methyl]cyclopentan-r-1-ol, (+) t-3-[1'-Acetylamino-1'-[(N-methoxy-N-methyl)aminocarbonyl]methyl]-c-4-tert -butoxycarbonylamino-t-1-[(trismethylthio)methyl]cyclopentan-r-1-ol, (+) t-3-(1'-Acetylamino-1'-formyl)methyl-c-4-tert-butoxycarbonylamino-t-1-[(tr is methylthio)methyl]cyclopentan-r-1-ol, (+) t-3-{(1'-Acetylamino-3'-ethyl-2'-oxo)pentyl}-c-4-tert-butoxycarbonylamino- t-1-{(trismethylthio)methyl]cyclopentan-r-1-ol, (+) t-3-{(1'-Acetylamino-3'-ethyl-2'-hydroxy)pentyl}-c-4-tert-butoxycarbonylam ino-t-1-{(trismethylthio)methyl}cyclopentan-r-1-ol, (+) Methyl c-3-{(1'-acetylamino-3'-ethyl-2'-hydroxy)pentyl}-t-4-tert-butoxycarbonyl-a mino-t-1-hydroxycyclopentan-r-1-carboxylate, (+) Methyl c-3-{(1'-acetylamino-3'-ethyl-2'-hydroxy)pentyl}-t-4-{(tert-butoxycarbonyl -amino-tert-butoxycarbonylimino)methyl}amino-t-1-hydroxycyclopentan-r-1-car boxylate, (+) c-3-{(1'-Acetylamino-3'-ethyl-2'-hydroxy)pentyl}-t-4-{aminoiminomethyl}-am ino-t-1-hydroxycyclopentan-r-1-carboxylic acid, (+) c-3-{(1'-Acetylamino-3'-ethyl-2'-hydroxy)pentyl}-t-4-{aminoiminomethyl}-am ino-t-1-hydroxycyclopentan-r-1-carboxylic acid, (+) 2-{3.beta.-(1'-Acetylamino-3'-ethyl)-2'-pentenyl-4.alpha.-tert-butoxycarbo nylamino-1-cyclopentylidene}-1,3-dithiane, (+) Methyl 3.beta.-(1'-Acetylamino-3'-ethyl)-2'-pentenyl-4.alpha.-(tert-butoxycarbony l)amino-cyclopentan-1-carboxylate, (+) Methyl 3.beta.-(1'-Acetylamino-3'-ethyl)-2'-pentenyl-4.alpha.-aminocyclopentan-1- carboxylate, (+) 3.beta.-(1'-Acetylamino-3'-ethyl)-2'-pentenyl-4.alpha.-aminocyclopentan-1- carboxylic acid, (+) Methyl 3.beta.-(1'-acetylamino-3'-ethyl)pentyl-4.alpha.-aminocyclopentan-1-carbox ylate, (+) 3.beta.-(1'-Acetylamino-3'-ethyl)pentyl-4.alpha.-aminocyclopentan-1-carbox ylate, (+) Methyl 3.beta.-(1'-Acetylamino-3'-ethyl)-2'-pentenyl-4.alpha.-aminocyclopentan-1- carboxylate, (+) Methyl 3.beta.-(1'-acetylamino-3'-ethyl)pentyl-4.alpha.-aminocyclopentan-1-carbox ylate, (+) 3.beta.-(1'-Acetylamino-3'-ethyl)pentyl-4.alpha.-aminocyclopentan-1-carbox ylic acid, (+) 2-{3.beta.-(1'-Acetylamino)-2'-pentenyl-4.alpha.-tert-butoxycarbonylamino- 1-cyclopent-ylidene}-1,3-dithiane, (+) Methyl 3.beta.-(1'-acetylamino)-2'-pentenyl-4.alpha.-tert-butoxycarbonylaminocycl opentan-1-carboxylate, (+) Methyl 3.beta.-(1'-acetylamino)pentyl-4.alpha.-tert-butoxyarbonylaminocyclopentan -1-carboxylate, (+) Methyl 3.beta.-(1'-acetylamino)pentyl-4.alpha.-aminocyclopentan-1-carboxylate, (+) 3.beta.-(1'-Acetylamino)pentyl-4.alpha.-aminocyclopentan-1-carboxylic acid, (+) Methyl cyclopent-3-ene-1-carboxylate, and (+) Ethyl cyclopent-3-ene-1-carboxylate, (+) Methyl t-3-(1'-acetylaminopentyl)-t-4-hydroxycyclopentan-r-1-carboxylate, (+) Methyl t-3-(1'-acetylaminopentyl)-t-4-hydroxycyclopentan-r-1-carboxylate, (+) Methyl t-3-(1-acetylamino-2-ethyl)butyl-t-4-hydroxycyclopentan-r-1-carboxylate, (+) Methyl t-3-[(1'-acetylamino-2'-ethyl)butyl]-t-4-hydroxycyclopentan-r-1-carboxylat e, (+) Methyl t-3-(1'-acetylamino-2'-propyl)pentyl-t-4-hydroxycyclopentan-r-1-carboxylat e, (+) Ethyl t-3-(1'-acetylamino-2'-cyclohexyl)ethyl-t-4-hydroxycyclopentan-r-1-carboxy late, (+) Ethyl t-3-(1'-acetylamino-2'-ethyl)hexyl-t-4-hydroxycyclopentan-r-1-carboxylate, (+) Ethyl t-3-(1'-acetylamino-2'-methyl)propyl-t-4-hydroxycyclopentan-r-1-carboxylat e, (+) Ethyl t-3-(1'-acetylamino-1'-cyclohexyl)methyl-t-4-hydroxycyclopentan-r-1-carbox ylate, (+) t-3-(1'-Acetylaminopentyl)-t-4-hydroxycyclopentan-r-1-carboxylic acid, (+) t-3-(1'-Acetylaminopentyl)-t-4-hydroxycyclopentan-r-1-carboxylic acid, (+) t-3-(1'-Acetylaminopentyl)-t-4-hydroxycyclopentan-r-1-carboxylic acid, (+) t-3-(1'-Acetylamino-2'-ethyl)butyl-t-4-hydroxycyclopentan-r-1-carboxylic acid, (+) t-3-(1'-Acetylamino-2'-ethyl)butyl-t-4-hydroxycyclopentan-r-1-carboxylic acid, (+) t-3-(1'-Acetylamino-2'-propyl)pentyl-t-4-hydroxycyclopentan-r-1-carboxylic acid, (+) t-3-(1'-Acetylamino-2'-cyclohexyl)ethyl-t-4-hydroxycyclopentan-r-1-carboxy lic acid, (+) t-3-(1'-Acetylamino-2'-ethyl)hexyl-t-4-hydroxycyclopentan-r-1-carboxylic acid, (+) t-3-(1'-Acetylamino-2'-methyl)propyl-t-4-hydroxycyclopentan-r-1-carboxylic acid, (+) t-3-(1'-Acetylamino-1'-cyclohexyl)methyl-t-4-hydroxycyclopentan-r-1-carbox ylic acid, (+) Methyl t-3-(1'-acetylaminopentyl)-t-4-methanesulfonyloxycyclopentan-r-1-carboxyla te, (+) Methyl t-3-(1'-acetylaminopentyl)-t-4-methanesulfonyloxycyclopentan-r-1-carboxyla te, (+) Methyl-t-3-(1'-Acetylamino-2'-ethyl)butyl-t-4-methanesulfonyloxycyclopenta n-r-1-carboxylate, (+) Methyl t-3-(1'-acetylamino-2'-propyl)pentyl-t-4-methanesulfonyloxycyclopentan-r-1 -carboxylate, (+) Methyl t-3-(1'-acetylaminopentyl)-c-4-azidocyclopentan-r-1-carboxylate, (+) Methyl-t-3-(1'-acetylaminopentyl)-c-4-azidocyclopentan-r-1-carboxylate, (+) Methyl t-3-[(1'-acetylamino-2'-ethyl)butyl]-c-4-azidocyclopentan-r-1-carboxylate, (+) Methyl t-3-(1'-acetylamino-2'-propyl)pentyl-c-4-azidocyclopentan-r-1-carboxylate, (+) Methyl t-3-(1'-acetylaminopentyl)-c-4-aminocyclopentan-r-1-carboxylate, (+) Methyl t-3-(1'-acetylaminopentyl)-c-4-aminocyclopentan-r-1-carboxylate, (+) Methy t-3-[(1'-acetylamino-2'-ethyl)butyl]-c-4-aminocyclopentan-r-1-carboxylate, (+) Methyl t-3-(1'-acetylamino-2'-propyl)pentyl-c-4-aminocyclopentan-r-1-carboxylate, (+) t-3-(1'-Acetylaminopentyl)-c-4-aminocyclopentan-r-1-carboxylic acid, (+) t-3-(1'-Acetylaminopentyl)-c-4-aminocyclopentan-r-1-carboxylic acid, (+) t-3-[(1'-Acetylamino-2'-ethyl)butyl]-c-4-aminocyclopentan-r-1-carboxylic acid, (+) t-3-(1'-Acetylamino-2'-propyl)pentyl-c-4-aminocyclopentan-r-1-carboxylic acid, (+) Methyl c-3-(1'-acetylaminopentyl)-c-4-hydroxycyclopentan-r-1-carboxylate, (+) c-3-(1'-Acetylaminopentyl)-c-4-hydroxycyclopentan-r-1-carboxylic acid, (+) Methyl c-3-(1'-acetylaminopentyl)-c-4-methanesulfonyloxycyclopentan-r-1-carboxyla te, (+) Methyl-c-3-(1'-acetylaminopentyl)-t-4-azidocyclopentan-r-1-carboxylate, (+) Methyl c-3-(1'-acetylaminopentyl)-t-4-aminocyclopentan-r-1-carboxylate, (+) c-3-(1'-Acetylaminopentyl)-t-4-aminocyclopentan-r-1-carboxylic acid, (+) Methyl t-3-(1'-acetylaminopentyl)-c-4-{(tert-butoxycarbonylamino-tert-butoxycarbo nylimino)methyl}aminocyclopentan-r-1-carboxylate, (+) Methyl t-4-(1'-acetylaminopentyl)-c-4-{(tert-butoxycarbonylamino-tert-butoxy carbonylimino)methyl}aminocyclopentan-r-1-carboxylate, (+) Methyl t-3-{(1'-acetylamino-2'-ethyl)butyl}-c-4-{(tert-butoxycarbonylamino-tert-b utoxy carbonylimino)methyl}aminocyclopentan-r-1-carboxylate, (+) Methyl t-3-(1'-acetylamino-2'-propyl)pentyl-c-4-{(tert-butoxycarbonylamino-tert-b utoxycarbonylimino)methyl}aminocyclopentan-r-1-carboxylate, (+) Methyl t-3-(1'-acetylaminopentyl)-c-4-{(aminoimino)methyl}aminocyclopentan-r-1-ca rboxylate, (+) Methyl t-3-(1'-acetylaminopentyl)-c-4-{(aminoimino)methyl}aminocyclopentan-r-1-ca rboxylate, (+) Methyl t-3-{(1'-acetylamino-2'-ethyl)butyl}-c-4-{(aminoimino)methyl}amino- cyclopentan-r-1-carboxylate, (+) t-3-(1'-Acetylamino-2'-propyl)pentyl-c-4-{(tert-butoxycarbonylamino-tert-b utoxycarbonylimino)methyl}aminocyclopentan-r-1-carboxylic acid, (+) t-3-(1'-Acetylaminopentyl)-c-4-{(aminoimino)methyl}aminocyclopentan-r-1-ca rboxylic acid, (+) t-3-(1'-Acetylaminopentyl)-c-4-{(aminoimino)methyl}aminocyclopentan-r-1-ca rboxylic acid, (+) t-3-{(1'-Acetylamino-2'-ethyl)butyl}-c-4-{(aminoimino)methyl}aminocyclopen tan-r-1-carboxylic acid, (+) t-3-(1'-Acetylamino-2'-propyl)pentyl-c-4-{(aminoimino)methyl}aminocyclopen tan-r-1-carboxylic acid, (+) Methyl c-3-(1'-acetylaminopentyl)-t-4-{(tert-butoxycarbonylamino-tert-butoxy carbonylimino)methyl}aminocyclopentan-r-1-carboxylate, (+) Methyl c-3-(1'-Acetylaminopentyl)-t-4-{(aminoimino)methyl}aminocyclopentan-r-1-ca rboxylate, (+) c-3-(1- Acetylaminopentyl)-t-4-{(aminoimino)methyl}aminocyclopentan-r-1-carboxylic acid, (1S,4R)-(-)-4-Aminocyclopent-2-en-1-carboxylic acid, (1R,4S)-(+)-4-Aminocyclopent-2-en-1-carboxylic acid, (+)-cis-4-Aminocyclopent-2-en-1-carboxylic acid, (1S,4R)-(-)-Methyl-4-aminocyclopent-2-en-1-carboxylate, (1S,4R)-(-)-Ethyl-4-aminocyclopent-2-en-1-carboxylate, (1R,4S)-(+)-Ethyl-4-aminocyclopent-2-en-1-carboxylate, (+)-cis-Methyl-4-aminocyclopent-2-en-1-carboxylate, (+)-cis-Ethyl-4-aminocyclopent-2-en-1-carboxylate, (1S,4R)-(-)-Methyl-4-tert-butoxycarbonylaminocyclopent-2-en-1-carboxylate, (1S,4R)-(-)-Ethyl-4-tert-butoxycarbonylaminocyclopent-2-en-1-carboxylate, (1R,4S)-(+)-Ethyl-4-tert-butoxycarbonylaminocyclopent-2-en-1-carboxylate, (+)-cis-Methyl-4-tert-butoxycarbonylaminocyclopent-2-en-1-carboxylate, (+)-cis-Ethyl-4-tert-butoxycarbonylaminocyclopent-2-en-1-carboxylate, (1S,2S,3R,4R,1'S)-(-)-Methy 3-(1'-acetyamino-2'-ethyl)butyl-4-tert-butoxycarbonyl-amino-2-hydroxycyclo pentan-1-carboxylate, (1S,2S,3R,4R,1'S)-(-)-Methyl 3-(1'-acetylamino-2'-propyl)pentyl-4-tert-butoxycarbonyl-amino-2-hydroxycy clopentan-1-carboxylate, (1S,2S,3R,4R,1'S)-(-)-Ethyl 3-(1'-acetylamino-2'-ethyl)butyl-4-tert-butoxycarbonyl-amino-2-hydroxycycl opentan-1-carboxylate, (1S,2S,3R,4R,1'S)-(-)-Methyl 3-(1'-acetylamino-2'-propyl)pentyl-4-tert-butoxycarbonyl-amino-2-hydroxycy clopentan-1-carboxylate, (1R,2R,3S,4S,1'R)-(+)-Ethyl 3-(1'-acetylamino-2'-ethyl)butyl-4-tert-butoxycarbonyl-amino-2-hydroxycycl opentan-1-carboxylate, (+)-Methyl t-3-(1'-acetylamino-2'-ethyl)butyl-c-4-tert-butoxycarbonylamino-t-2-hydrox ycyclopentan-r-1-carboxylate, (+)-Methyl t-3-(1'-acetylamino-2'-propyl)pentyl-c-4-tert-butoxycarbonylamino-t-2-hydr oxycyclopentan-r-1-carboxylate, (+)-Methyl t-3-(1'-acetylamino-3'-ethyl)pentyl-c-4-tert-butoxycarbonylamino-t-2-acety loxycyclopentan-r-1-carboxylate, (+)-Methyl t-3-(1'-acetylamino-n-butyl)-c-4-tert-butoxycarbonylamino-t-2-acetyloxy-cy clopentan-r-1-carboxylate, (+)-Ethyl t-3-(1'-acetylamino-2'-ethyl)butyl-c-4-tert-butoxycarbonylamino-t-2-hydrox ycyclopentan-r-1-carboxylate, (+)-Ethyl t-3-(1'-acetylamino-2'-methyl)butyl-c-4-tert-butoxycarbonylamino-t-2-hydro xycyclopentan-r-1-carboxylate, (+)-Ethyl t-3-(1'-acetylamino-2'-methyl)propyl-c-4-tert-butoxycarbonylamino-t-2-hydr oxycyclopentan-r-1-carboxylate, (1S,2S,3R,4R,1'S)-(-)-Methyl 3-(1'-acetylamino-2'-ethyl)butyl-4-amino-2-hydroxy-cyclopentan-1-carboxyla te, (1S,2S,3R,4R,1'S)-(-)-Methyl 3-(1'-acetylamino-2'-propyl)pentyl-4-amino-2-hydroxycyclopentan-1-carboxyl ate, (1S,2S,3R,4R,1'S)-(-)-Ethyl 3-(1'-acetylamino-2'-ethyl)butyl-4-amino-2-hydroxycyclo-pentan-1-carboxyla te, 1R,2R,3S,4S,1'R)-(+)-Ethyl 3-(1'-acetylamino-2'-ethyl)butyl-4-amino-2-hydroxy-cyclopentan-1-carboxyla te, (+)-Methyl t-3-(1'-acetylamino-2'-ethyl)butyl-c-4-amino-t-2-hydroxycyclopentan-r-1-ca rboxylate, (+)-Methyl t-3-(1'-acetylamino-2'-propyl)pentyl-c-4-amino-t-2-hydroxycyclopentan-r-1- carboxylate, (+)-Methyl t-3-(1'-acetylamino-3'-ethyl)pentyl-c-4-amino-t-2-acetyloxycyclopentan-r-1 -carboxylate, (+)-Methyl t-3-(1'-acetylamino-n-butyl)-c-4-amino-t-2-acetyloxycyclopentan-r-1-carbox ylate, (+)-Ethyl t-3-(1'-acetylamino-2'-ethyl)butyl-c-4-amino-t-2-hydroxycyclopentan-r-1-ca rboxylate, (+)-Ethyl t-3-(1'-acetylamino-2'-methyl)butyl-c-4-amino-t-2-hydroxycyclopentan-r-1-c arboxylate, (+)-Ethyl t-3 -(1'-acetylamino-2'-methyl)propyl-c-4-amino-t-2-hydroxycyclopentan-r-1-car boxylate, (1S,2S,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-ethyl)butyl-4-amino-2-hydroxycy clopentan-1-carboxylic acid, (1R,2R,3S,4S,1'R)-(+)-3-(1'-Acetylamino-2'-ethyl)butyl-4-amino-2-hydroxy-c yclopentan-1-carboxylic acid, (+)-t-3-(1'-Acetylamino-2'-ethyl)butyl-c-4-amino-t-2-hydroxycyclopentan-r- 1-carboxylic acid, (+)-t-3-(1'-Acetylamino-2'-propyl)pentyl-c-4-amino-t-2-hydroxycyclopentan- r-1-carboxylic acid, (+)-t-3-(1'-Acetylamino-3'-ethyl)pentyl-c-4-amino-t-2-hydroxycyclopentan-r -1-carboxylic acid, (+)-t-3-(1'-Acetylamino-n-butyl)-c-4-amino-t-2-hydroxycyclopentan-r-1-carb oxylic acid, (+)-t-3-(1'-Acetylamino-2'-methyl)butyl-c-4-amino-t-2-hydroxycyclopentan-r -1-carboxylic acid, (+)-t-3-(1'-Acetylamino-2'-methyl)propyl-c-4-amino-t-2-hydroxycyclopentan- r-1-carboxylic acid, (1S,2S,3R,4R,1'S)-(-)-Ethyl 3-(1'-acetylamino-2'-ethyl)butyl-4-{(tert-butoxycarbo-nyl-amino-tert-butox ycarbonylimino)methyl}amino-2-hydroxycyclopentan-1-carboxylate, (+)-Methyl t-3-(1'-acetylamino-2'-ethyl)butyl-c-4-{(tert-butoxycarbonylamino-tert-but oxycarbonylimino)methyl}amino-t-2-hydroxycyclopentan-r-1-carboxylate, (+)-Methyl t-3-(1'-acetylamino-3'-ethyl)pentyl-c-4-{(tert-butoxycarbonylamino-tert-bu toxycarbonylimino)methyl}amino-t-2-acetyloxycyclopentan-r-1-carboxylate, (+)-Methyl t-3-(1'-acetylamino-n-butyl)-c-4-{(tert-butoxycarbonylamino-tert-butoxycar bonylimino)methyl}amino-t-2-acetyloxycyclopentan-r-1-carboxylate, (1S,2S,3R,4R,1'S)-(-)-Ethyl 3-(1'-acetylamino-2'-ethyl)butyl-4-{(N-tert-butoxycarbonyl-N-methylamino-N '-tert-butoxycarbonylimino)methyl}amino-2-hydroxycyclopentan-1-carboxylate, (1S,2S,3R,4R,1'S)-(-)-Ethyl 3-(1'-acetylamino-2'-ethyl)butyl-4-{(amino-imino)methyl}-amino-2-hydroxycy clopentan-1-carboxylate, (+)-Methyl t-3-(1'-acetylamino-2'-ethyl)butyl-c-4-{(amino-imino)methyl}amino-t-2-hydr oxycyclopentan-r-1-carboxylate, (+)-Methyl t-3-(1'-acetylamino-3'-ethyl)pentyl-c-4-{(amino-imino)methyl}amino-t-2-ace tyloxycyclopentan-r-1-carboxylate, (+)-Methyl t-3-(1'-acetylamino-n-butyl)-c-4-{(amino-imino)methyl}amino-t-2-acetyloxyc yclopentan-r-1-carboxylate, (1S,2S,3R,4R,1'S)-(-)-Ethyl-3-(1'-acetylamino-2'-ethyl)butyl-4-{(N-methyla mino-imino)methyl}amino-2-hydroxycyclopentan-1-carboxylate, (1S,2S,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-ethyl)butyl-4-{(aminoimino) methyl}amino-2-hydroxycyclopentan-1-carboxylic acid, (+)-t-3-(1'-Acetylamino-2'-ethyl)butyl-c-4-{(amino-imino)methyl}amino-t-2- hydroxycyclopentan-r-1-carboxylic acid, (+)-t-3-(1'-Acetylamino-3'-ethyl)pentyl-c-4-{(amino-imino)methyl}amino-t-2 -hydroxycyclopentan-r-1-carboxylic acid, (+)-t-3-(1'-Acetylamino-n-butyl)-c-4-{(amino-imino)methyl}amino-t-2-hydrox ycyclopentan-r-1-carboxylic acid, (1S,2S,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-ethyl)butyl-4-{(N-methylamino-i mino)methyl}amino-2-hydroxycyclopentan-1-carboxylic acid, (1S,2S,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-propyl)pentyl-4-{(amino-imino)m ethyl}amino-2-hydroxycyclopentan-1-carboxylic acid, (1S,2S,3R,4R,1'S)-(-)-Methyl 3-(1'-acetylamino-2'-ethyl)butyl-4-tert-butoxycarbonyl-amino-2-(N-imidazol yl-thiocarbonyloxy)cyclopentan-1-carboxylate, (1S,2S,3R,4R,1'S)-(-)-Methyl 3-(1'-acetylamino-2'-propyl)pentyl-4-tert-butoxycarbonylamino-2-(N-imidazo lyl-thiocarbonyloxy)cyclopentan-1-carboxylate, (1S,2S,3R,4R,1'S)-(-)-Ethyl 3-(1'-acetylamino-2'-ethyl)butyl-4-tert-butoxycarbonyl-amino-2-(N-imidazol yl-thiocarbonyloxy)cyclopentan-1-carboxylate, (1S,2S,3R,4R,1'S)-(-)-Methyl 3-(1'-acetylamino-2'-propyl)pentyl-4-tert-butoxycarbonyl-amino-2-(N-imidaz olyl-thiocarbonyloxy)cyclopentan-1-carboxylate, (+)-Methyl t-3-(1'-acetylamino-2'-ethyl)butyl-c-4-tert-butoxycarbonylamino-t-2-(N-imi dazolyl-thiocarbonyloxy)cyclopentan-r-1-carboxylate, (1R,3R,4R,1'S)-(-)-Methyl 3-(1'-acetylamino-2'-ethyl)butyl-4-tert-butoxycarbonyl-aminocyclopentan-1- carboxylate, (1R,3R,4R,1'S)-(-)-Methyl 3-(1'-acetylamino-2'-propyl)pentyl-4-tert-butoxycarbonyl-aminocyclopentan- 1-carboxylate, (1R,3R,4R,1'S)-(-)-Ethyl 3-(1'-acetylamino-2'-ethyl)butyl-4-tert-butoxycarbonyl-amino-cyclopentan-1 -carboxylate, (1R,3R,4R,1'S)-(-)-Methyl 3-(1'-acetylamino-2'-propyl)pentyl-4-tert-butoxycarbonyl-aminocyclopentan- 1-carboxylate, (+)-Methyl t-3-(1'-acetylamino-2'-ethyl)butyl-c-4-tert-butoxycarbonylaminocyclo-penta n-1-carboxylate, (1R,3R,4R,1'S)-(-)-Methyl 3-(1'-acetylamino-2'-ethyl)butyl-4-aminocyclopentan-1-carboxylate, (1R,3R,4R,1'S)-(-)-Methyl 3-(1'-acetylamino-2'-propyl)pentyl-4-aminocyclopentan-1-carboxylate, (1R,3R,4R,1'S)-(-)-Ethyl 3-(1'-acetylamino-2'-ethyl)butyl-4-aminocyclopentan-1-carboxylate, (1R,3R,4R,1'S)-(-)-Ethyl-3-(1'-acetylamino-2'-propyl)pentyl-4-aminocyclope ntan-1-carboxylate, (+)-Methyl t-3-(1'-acetylamino-2'-ethyl)butyl-c-4-aminocyclopentan-1-carboxylate, (1R,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-ethyl)butyl-4-aminocyclopentan-1-c arboxylic acid, (+)-t-3-(1'-Acetylamino-2'-ethyl)butyl-c-4-aminocyclopentan-1-carboxylic acid, (1R,3R,4R,1'S)-(-)-Ethyl 3-(1'-acetylamino-2'-ethyl)butyl-4-{(tert-butoxycarbonyl-amino-tert-butoxy carbonylimino)methyl}aminocyclopentan-1-carboxylate, (1R,3R,4R,1'S)-(-)-Ethyl 3-(1'-acetylamino-2'-propyl)pentyl-4-{(tert-butoxycarbonyl-amino-tert-buto xycarbonylimino)methyl}aminocyclopentan-1-carboxylate, (+)-Methyl t-3-(1'-acetylamino-2'-ethyl)butyl-c-4-{(tert-butoxycarbonylamino-tert-but oxycarbonylimino)methyl}aminocyclopentan-r-1-carboxylate, (1R,3R,4R,1'S)-(-)-Ethyl 3-(1'-acetylamino-2'-ethyl)butyl-4-{(N-tert-butoxycarbonyl-N-methylamino-N '-tert-butoxycarbonylimino)methyl}aminocyclopentan-1-carboxylate, (1R,3R,4R,1'S)-(-)-Ethyl 3-(1'-acetylamino-2'-ethyl)butyl-4-{(amino-imino)methyl}-aminocyclopentan- 1-carboxylate, (1R,3R,4R,1'S)-(-)-Ethyl 3-(1'-acetylamino-2'-propyl)pentyl-4-{(amino-imino)-methyl}aminocyclopenta n-1-carboxylate, (+)-Methyl t-3-(1'-acetylamino-2'-ethyl)butyl-c-4-{(amino-imino)methyl}-aminocyclo-pe ntan-r-1-carboxylate, (1R,3R,4R,1'S)-(-)-Ethyl-3-(1'-acetylamino-2'-ethyl)butyl-4-{(N-methylamin o-imino)methyl}aminocyclopentan-1-carboxylate, (1R,3R,4R,1'S)-(-)-3-(1'-Acetylamino-}2'-ethyl)butyl-4-(aminoimino)methyl- aminocyclopentan-1-carboxylic acid, (1R,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-propyl)pentyl-4-{(amino-imino)meth yl}aminocyclopentan-1-carboxylic acid, (+)-t-3-(1'-Acetylamino-2'-ethyl)butyl-c-4-{(amino-imino)methyl}-aminocycl opentan-r-1-carboxylic acid, (1R,3R,4R,1'S)-(-)-3 -(1'-Acetylamino-2'-ethyl)butyl-4-{(N-methylamino-imino)methyl}aminoclopen tan-1-carboxylic acid, (1S,2S,3R,4R,1'S)-(-)-Methyl 3-(1'-acetylamino-2'-ethyl)butyl-4-tert-butoxy-carbonylamino-2-methanesulf onyloxycyclopentan-1-carboxylate, (3R,4R,1'S)-(-)-Methyl-3-(1'-acetylamino-2'-ethyl)butyl-4-tert-butoxycarbo nyl-amino-cyclopent-1-en-1-carboxylate, (3R,4R,1'S)-(-)-Methyl 3-(1'-acetylamino-2'-ethyl)butyl-4-aminocyclopent-1-en-1-carboxylate hydrochloride, (3R,4R,1'S)-(-) 3-(1'-Acetylamino-2'-ethyl)butyl-4-aminocyclopent-1-en-1-carboxylic acid, (3R,4R,1'S)-(-)-Methyl 3-(1'-acetylamino-2'-ethyl)butyl-4-{(tert-butoxycarbonyl-amino-tert-butoxy carbonylimino)methyl}aminocyclopent-1-en-1-carboxylate, (3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-ethyl)butyl-4-{(tert-butoxycarbonylam ino-tert-butoxycarbonylimino)methyl}aminocyclopent-1-en-1-carboxylic acid, (3R,4R,1's)-(-)-3-(1'-Acetylamino-2'-ethyl)butyl-4-{(amino-imino)methyl}am ino-cyclopent-1-en-1-carboxylic acid; and pharmaceutically acceptable salts thereof. 8. The compound of claim 1 being selected from the group consisting of (+) t-3-(1'-Acetylamino-2'-ethyl)butyl-t-4-hydroxycyclopentan-r-1-carboxylic acid (+) t-3-[(1'-Acetylamino-2'-ethyl)butyl]-c-4-aminocyclopentan-r-1-carboxylic acid (1S,2S,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-ethyl)butyl-4-amino-2-hydroxycy clo pentan-1-carboxylic acid, (+)-t-3-(1'-Acetylamino-2'-ethyl)butyl-c-4-amino-t-2-hydroxycyclopentan-r- 1-carboxylic acid, (+)-t-3-(1'-Acetylamino-2'-propyl)pentyl-c-4-amino-t-2-hydroxycyclopentan- r-1-carboxylic acid, (+)-t-3-(1'-Acetylamino-n-butyl)-c-4-amino-t-2-hydroxycyclopentan-r-1-carb oxylic acid, (+)-t-3-(1'-Acetylamino-2'-methyl)butyl-c-4-amino-t-2-hydroxycyclopentan-r -1-carboxylic acid, (1S,2S,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-ethyl)butyl-4-{aminoimino)methy l}amino-2-hydroxycyclopentan-1-carboxylic acid, (+)-t-3-(1'-Acetylamino-2'-ethyl)butyl-c-4-{amino-imino)methyl}amino-t-2-h ydroxycyclopentan-r-1-carboxylic acid, (+)-t-3-(1'-Acetylamino-3'-ethyl)pentyl-c-4-{(amino-imino)methyl}amino-t-2 -hydroxycyclopentan-r-1-carboxylic acid, (+)-t-3-(1'-Acetylamino-n-butyl)-c-4-[(amino-imino)methyl]amino-t-2-hydrox ycyclopentan-r-1-carboxylic acid, (1S,2S,3R,4,R1'S)-(-)-3-(1'-Acetylamino-2'-ethyl)butyl-4-{(N-methylamino-i mino)methyl}amino-2-hydroxycyclopentan-1-carboxylic acid, (1S,2S,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-propyl)pentyl-4-{(amino-imino)m ethyl}amino-2-hydroxycyclopentan-1-carboxylic acid, (1R,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-ethyl)butyl-4-aminocyclopentan-1-c arboxylic acid, (+)-t-3-(1'-Acetylamino-2'-ethyl)butyl-c-4-aminocyclopentan-1-carboxylic acid, (1R,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-ethyl)butyl-4-(aminoimino)methyl-a minocyclopentan-1-carboxylic acid, (1R,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-propyl)pentyl-4-{(amino-imino)meth yl}aminocyclopentan-1-carboxylic acid, (+)-t-3-(1'-Acetylamino-2'-ethyl)butyl-c-4-{(amino-imino)methyl}-aminocycl opentan-r-1-carboxylic acid, (1R,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-ethyl)butyl-4-{(N-methylamino-imin o)methyl}aminocyclopentan-1-carboxylic acid, (3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-ethyl)butyl-4-{(amino-imino)methyl}am ino-cyclopent-1-en-1-carboxylic acid; and pharmaceutically acceptable salts thereof. 9. The compound of claim 7 being (1S,2S,3R,4R,1'S)-(-)-Methyl-3-(1'-acetylamino-2'-ethyl)butyl-4-amino-2-hy droxy-cyclopentan-1-carboxylate; or a pharmaceutically acceptable salt thereof. 10. The compound of claim 7 being (1S,2S,3R,4R,1'S)-(-)-Methyl-3-(1'-acetylamino-2'-propyl)pentyl-4-amino-2- hydroxy-cyclopentan-1-carboxylate; or a pharmaceutically acceptable salt thereof. 11. The compound of claim 7 being (1S,2S,3R,4R,1'S)-(-)-Ethyl-3-(1'-acetylamino-2'-ethyl)butyl-4-amino-2-hyd roxy-cyclopentan-1-carboxylate; or a pharmaceutically acceptable salt thereof. 12. The compound of claim 9 being (1R,2R,3S,4S,1'R)-(+)-Ethyl-3-(1'-acetylamino-2'-ethyl)butyl-4-amino-2-hyd roxy-cyclopentan-1-carboxylate; or a pharmaceutically acceptable salt thereof. 13. The compound of claim 7 being (1S,2S,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-ethyl)butyl-4-amino-2-hydroxy-c yclopentan-1-carboxylic acid; or a pharmaceutically acceptable salt thereof. 14. The compound of claim 7 being (1R,2R,3S,4S,1'R)-(+)-3-(1'-Acetylamino-2'-ethyl)butyl-4-amino-2-hydroxy-c yclopentan-1-carboxylic acid; or a pharmaceutically acceptable salt thereof. 15. The compound of claim 7 being (1S,2S,3R,4R,1'S)-(-)-Ethyl-3-(1'-acetylamino-2'-ethyl)butyl-4-[(aminoimin o)-methyl]amino-2-hydroxy-cyclopentan-1-carboxylate; or a pharmaceutically acceptable salt thereof. 16. The compound of claim 7 being (1S,2S,3R,4R,1'S)-(-)-Ethyl-3-(1'-acetylamino-2'-ethyl)butyl-4-[(N-methyla mino-imino)methyl]amino-2-hydroxycyclopentan-1-carboxylate; or a pharmaceutically acceptable salt thereof. 17. The compound of claim 7 being (3R,4R,1'S)-(-)-Methyl-3-(1'-acetylamino-2'-ethyl)butyl-4-aminocyclopent-1 -en-1-carboxylate; or a pharmaceutically acceptable salt thereof. 18. The compound of claim 7 being (3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-ethyl)butyl-4-aminocyclopent-1-en-1-c arboxylic acid; or a pharmaceutically acceptable salt thereof. 19. The compound of claim 7 being (3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-ethyl)butyl-4-[(aminoimino)methyl]ami no-cyclopent-1-en-1-carboxylic acid; or a pharmaceutically acceptable salt thereof. 20. The compound of claim 7 being (1S,2S,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-ethyl)butyl-4-[(aminoimino)meth yl]-amino-2-hydroxycyclopentan-1-carboxylic acid; or a pharmaceutically acceptable salt thereof. 21. The compound of claim 7 being (1S,2S,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-ethyl)butyl-4-[(N-methylamino-i mino)methyl]amino-2-hydroxycyclopentan-1-carboxylic acid; or a pharmaceutically acceptable salt thereof. 22. The compound of claim 7 being (1S,2S,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-propyl)pentyl-4-[(aminoimino)-m ethyl]amino-2-hydroxycyclopentan-1-carboxylic acid; or a pharmaceutically acceptable salt thereof. 23. The compound of claim 7 being (1R,3R,4R,1'S)-(-)-Methyl-3-(1'-acetylamino-2'-ethyl)butyl-4-aminocyclopen tan-1-carboxylate; or a pharmaceutically acceptable salt thereof. 24. The compound of claim 7 being (1R,3R,4R,1'S)-(-)-Ethyl-3-(1'-acetylamino-2'-ethyl)butyl-4-aminocyclopent an-1-carboxylate; or a pharmaceutically acceptable salt thereof. 25. The compound of claim 7 being (1R,3R,4R,1'S)-(-)-Ethyl-3-(1'-acetylamino-2'-propyl)pentyl-4-aminocyclo-p entan-1-carboxylate; or a pharmaceutically acceptable salt thereof. 26. The compound of claim 7 being (1R,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-ethyl)butyl-4-aminocyclopentan-1-c arboxylic acid; or a pharmaceutically acceptable salt thereof. 27. The compound of claim 7 being (1R,3R,4R,1'S)-(-)-Ethyl-3-(1'-acetylamino-2'-ethyl)butyl-4-[(aminoimino)- methyl]aminocyclopentan-1-carboxylate; or a pharmaceutically acceptable salt thereof. 28. The compound of claim 7 being (1R,3R,4R,1'S)-(-)-Ethyl-3-(1'-acetylamino-2'-ethyl)butyl-4-[(N-methylamin o-imino)methyl]aminocyclopentan-1-carboxylate; or a pharmaceutically acceptable salt thereof. 29. compound of claim 7 being (1R,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-ethyl)butyl-4-[(aminoimino)methyl] -aminocyclopentan-1-carboxylic acid; or a pharmaceutically acceptable salt thereof. 30. The compound of claim 7 being (1R,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-propyl)pentyl-4-[(aminoimino)methy l]-aminocyclopentan-1-carboxylic acid; or a pharmaceutically acceptable salt thereof. 31. The compound of claim 7 being (1R,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-ethyl)butyl-4-[(N-methylamino-imin o)methyl]aminocyclopentan-1-carboxylic acid; or a pharmaceutically acceptable salt thereof. 32. The compound of claim 7 being (1S,2S,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-propyl)pentyl-4-amino-2-hydroxy -cyclopentan-1-carboxylic acid; or a pharmaceutically acceptable salt thereof. 33. The compound of claim 7 being (1R,2R,3S,4S,1'R)-(+)-3-(1'-Acetylamino-2'-propyl)pentyl-4-amino-2-hydroxy -cyclopentan-1-carboxylic acid; or a pharmaceutically acceptable salt thereof. 34. The compound of claim 7 being (1R,2R,3S,4S,1'R)-(+)-3-(1'-Acetylamino-2'-ethyl)butyl-4-[(aminoimino)-met hyl]-amino-2-hydroxycyclopentan-1-carboxylic acid; or a pharmaceutically acceptable salt thereof. 35. The compound of claim 7 being (1R,2R,3S,4S,1'R)-(+)-3-(1'-Acetylamino-2'-propyl)pentyl-4-[(aminoimino)-m ethyl]amino-2-hydroxycyclopentan-1-carboxylic acid; or a pharmaceutically acceptable salt thereof. 36. The compound of claim 7 being (1R,3R,4R,1'S)-(-)-3-(1'-Acetylamino-2'-propyl)pentyl-4-aminocyclo-pentan- 1-carboxylic acid; or a pharmaceutically acceptable salt thereof. 37. The compound of claim 7 being (1S,3S,4S,1'R)-(+)-3-(1'-Acetylamino-2'-ethyl)butyl-4-aminocyclopentan-1-c arboxylic acid; or a pharmaceutically acceptable salt thereof. 38. The compound of claim 7 being (1S,3S,4S,1'R)-(+)-3-(1'-Acetylamino-2'-ethyl)butyl-4-[(aminoimino)methyl] -aminocyclopentan-1-carboxylic acid; or a pharmaceutically acceptable salt thereof. 39. The compound of claim 7 being (1S,3S,4S,1'R)-(+)-3-(1'-Acetylamino-2'-propyl)pentyl-4-[(aminoimino)methy l]-aminocyclopentan-1-carboxylic acid; or a pharmaceutically acceptable salt thereof. 40. A composition for inhibiting influenza virus nueraminidase, comprising: a pharmaceutically acceptable carrier and an amount effective for inhibiting influenza virus nueraminidase of a compound according to claim 1. 41. A method of treating influenza virus infection, comprising the step of: administering to a patient in need thereof a pharmaceutically acceptable carrier and an amount effective for inhibiting influenza virus nueraminidase of a compound according to claim 1.