Claims for Patent: 4,572,912

Summary for Patent: 4,572,912

Title:	Thiazolidine derivatives, their preparation and compositions containing them
Abstract:	The compounds of formula (I): ##STR1## [in which: R.sup.1 and R.sup.2 are the same or different and each represents hydrogen or C.sub.1 -C.sub.5 alkyl; R.sup.3 represents hydrogen, an acyl group, a (C.sub.1 -C.sub.6 alkoxy)carbonyl group or an aralkyloxycarbonyl group; R.sup.4 and R.sup.5 are the same or different and each represents hydrogen, C.sub.1 -C.sub.5 alkyl or C.sub.1 -C.sub.5 alkoxy, or R.sup.4 and R.sup.5 together represent a C.sub.1 14 C.sub.4 alkylenedioxy group; n is 1, 2 or 3; W represents the --CH.sub.2 --, >CO or >CH--OR.sup.6 group (in which R.sup.6 represents any one of the atoms or groups defined for R.sup.3 and may be the same as or different from R.sup.3); and Y and Z are the same or different and each represents oxygen or imino] and pharmaceutically acceptable salts thereof have various valuable therapeutic effects on the blood system and may be prepared by a process which includes reacting a corresponding halopropionic acid derivative with thiourea.
Inventor(s):	Yoshioka; Takao (Hiromachi, JP), Kitazawa; Eiici (Hiromachi, JP), Kurumada; Tomoyuki (Hiromachi, JP), Yamazaki; Mitsuo (Hiromachi, JP), Hasegawa; Kazou (Hiromachi, JP)
Assignee:	Sankyo Company Limited (Tokyo, JP)
Application Number:	06/644,996
Patent Claims:	1. Compounds of formula (I): ##STR19## in which: R.sup.1 and R.sup.2 are the same or different and each represents hydrogen or a C.sub.1 -C.sub.5 alkyl group; R.sup.3 represents hydrogen; C.sub.1 -C.sub.6 aliphatic acyl; (C.sub.5 -C.sub.7 cycloalkane)carbonyl; benzoyl, benzoyl substituted with one to three substituents selected from the group of C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, hydroxy, halogen, nitro, amino and di(C.sub.1 -C.sub.4 alkyl)amino; naphthoyl; 4-7 membered heterocyclic acyl wherein heterocyclic moiety has O, S or N hetero atoms; phenyl(C.sub.2 -C.sub.3)aliphatic acyl; cinnamoyl; (C.sub.1 -C.sub.6 alkoxy)carbonyl; or benzoyloxycarbonyl; R.sup.4 and R.sup.5 are the same or different and each represents hydrogen, a C.sub.1 -C.sub.5 alkyl group or a C.sub.1 -C.sub.5 alkoxy group, or R.sup.4 and R.sup.5 together represent a C.sub.1 -C.sub.4 alkylenedioxy group; n is 1, 2 or 3; W represents the --CH.sub.2 --, >CO or >CH--OR.sup.6 group (in which R.sup.6 represents any one of the atoms or groups defined for R.sup.3 and may be the same as or different from R.sup.3); and Y and Z are the same or different and each represents the oxygen atom or the imino group; and pharmaceutically acceptable salts thereof. 2. Compounds as claimed in claim 1, in which; R.sup.3 represents hydrogen, a C.sub.1 -C.sub.6 aliphatic acyl group, one of said aromatic acyl groups or one of said heterocyclic acyl groups. 3. Compounds as claimed in claim 1, in which: Y represents an oxygen atom; R.sup.1 and R.sup.2 are the same or different and each represents hydrogen or a C.sub.1 -C.sub.5 alkyl group; R.sup.3 represents hydrogen, a C.sub.1 -C.sub.6 aliphatic acyl group, one of said aromatic acyl groups or a pyridinecarbonyl group; and R.sup.4 and R.sup.5 are the same or different and each represents hydrogen, a C.sub.1 -C.sub.5 alkyl group or a C.sub.1 or C.sub.2 alkoxy group. 4. Compounds as claimed in claim 3, in which: R.sup.1, R.sup.2, R.sup.4 and R.sup.5 are the same or different and each represents hydrogen or a C.sub.1 -C.sub.5 alkyl group; n is 1 or 2; and W represents the --CH.sub.2 -- or >CO group. 5. Compounds as claimed in claim 4, in which R.sup.3 represents a hydrogen atom, a C.sub.1 -C.sub.5 aliphatic acyl group, or the benzoyl or nicotinoyl group. 6. Compounds as claimed in claim 5, in which: R.sup.1 and R.sup.4 are the same or different and each represents a C.sub.1 -C.sub.5 alkyl group; R.sup.2 and R.sup.5 are the same or different and each represents the hydrogen atom or the methyl group; and R.sup.3 represents hydrogen or a C.sub.1 -C.sub.4 aliphatic acyl group. 7. Compounds as claimed in claim 1, in which: W represents the --CH.sub.2 -- or >CO group; Y and Z both represent oxygen atoms; n is 1 or 2; R.sup.1 and R.sup.4 are the same or different and each represents a C.sub.1 -C.sub.4 alkyl group; R.sup.2 and R.sup.5 are the same or different and each represents the hydrogen atom or the methyl group; and R.sup.3 represents hydrogen or a C.sub.1 -C.sub.4 aliphatic acyl group. 8. Compounds as claimed in claim 7, in which n is 1. 9. Compounds as claimed in claim 7 or claim 8, in which W represents the --CH.sub.2 -- group. 10. Compounds as claimed in claim 1, selected from the group consisting of: 5-[4-(6-hydroxy-2,5,7,8-tetramethylchroman-2-ylmethoxy)benzyl]thiazolidine- 2,4-dione 5-[4-(2-ethyl-6-hydroxy-5,7,8-trimethylchroman-2-ylmethoxy)benzyl]thiazolid ine-2,4-dione 5-[4-(6-hydroxy-5,7,8-trimethylchroman-2-ylmethoxy)benzyl]thiazolidine-2,4- dione 5-{4-[2-(6-hydroxy-2,5,7,8-tetramethylchroman-2-yl)ethoxy]benzyl}thiazolidi ne-2,4-dione 5-{4-[2-(7-t-butyl-6-hydroxy-2-methylchroman-2-yl)ethoxy]benzyl}thiazolidin e-2,4-dione 5-{4-[2-(6-hydroxy-7,8-dimethoxy-2,5-dimethylchroman-2-yl)ethoxy]benzyl}thi azolidine-2,4-dione 5-[4-(6-hydroxy-2,7-dimethylchroman-2-ylmethoxy)benzyl]thiazolidine-2,4-dio ne 5-[4-(6-hydroxy-2-isobutyl-5,7,8-trimethylchroman-2-ylmethoxy)benzyl]thiazo lidine-2,4-dione 5-[4-(6-hydroxy-2,5,7,8-tetramethylchroman-2-ylmethoxy)benzyl]-2-iminothiaz olidin-4-one 5-[4-(7-t-butyl-6-hydroxy-2-methylchroman-2-ylmethoxy)benzyl]-2-iminothiazo lidin-4-one 5-[4-(2-ethyl-6-hydroxy-5,7,8-trimethylchroman-2-ylmethoxy)benzyl]-2-iminot hiazolidin-4-one 5-[4-(6-hydroxy-5,7,8-trimethylchroman-2-ylmethoxy)benzyl]-2-iminothiazolid in-4-one 5-[4-(6-hydroxy-2,7-dimethylchroman-2-ylmethoxy)benzyl]-2-iminothiazolidin- 4-one 5-[4-(6-acetoxy-2,5,7,8-tetramethylchroman-2-ylmethoxy)benzyl]thiazolidine- 2,4-dione 5-[4-(6-benzoyloxy-2,5,7,8-tetramethylchroman-2-ylmethoxy)benzyl]thiazolidi ne-2,4-dione 5-[4-(6-butyryloxy-2,5,7,8-tetramethylchroman-2-ylmethoxy)benzyl]thiazolidi ne-2,4-dione 5-[4-(2,5,7,8-tetramethyl-6-nicotinoyloxychroman-2-ylmethoxy)benzyl]thiazol idine-2,4-dione 5-[4-(6-hydroxy-2,5,7,8-tetramethyl-4-oxochroman-2-ylmethoxy)benzyl]thiazol idine-2,4-dione 5-[4-(7-t-butyl-6-hydroxy-2-methyl-4-oxochroman-2-ylmethoxy)benzyl]thiazoli dine-2,4-dione 5-[4-(6-hydroxy-2-isobutyl-5,7,8-trimethyl-4-oxochroman-2-ylmethoxy)benzyl] thiazolidine-2,4-dione 5-[4-(6-hydroxy-2,5,7,8-tetramethyl-4-oxochroman-2-ylmethoxy)benzyl]-2-imin othiazolidin-4-one 5-[4-(7-t-butyl-6-hydroxy-2-methyl-4-oxochroman-2-ylmethoxy)benzyl]-2-imino thiazolidin-4-one 5-[4-(6-hydroxy-2-isobutyl-5,7,8-trimethyl-4-oxochroman-2-ylmethoxy)benzyl] -2-iminothiazolidin-4-one 5-[4-(6-acetoxy-2,5,7,8-tetramethyl-4-oxochroman-2-ylmethoxy)benzyl]thiazol idine-2,4-dione 5-[4-(6-acetoxy-5,7,8-trimethylchroman-2-ylmethoxy)benzyl]-2-iminothiazolid in-4-one 5-{4-[2-(6-acetoxy-7-t-butyl-2-methylchroman-2-yl)ethoxy]benzyl}-2-iminothi azolidin-4-one 5-{4-[2-(6-acetoxy-7,8-dimethoxy-2,5-dimethylchroman-2-yl)ethoxy]benzyl}-2- iminothiazolidin-4-one and pharmaceutically acceptable salts thereof. 11. The compound as claimed in claim 1, 5-[4-(6-hydroxy-2,5,7,8-tetramethylchroman-2-ylmethoxy)benzyl]thiazolidine- 2,4-dione and pharmaceutically acceptable salts thereof. 12. The compound as claimed in claim 1, 5-[4-(2-ethyl-6-hydroxy-5,7,8-trimethylchroman-2-ylmethoxy)benzyl]thiazolid ine-2,4-dione and pharmaceutically acceptable salts thereof. 13. The compound as claimed in claim 1, 5-{4-[2-(7-t-butyl-6-hydroxy-2-methylchroman-2-yl)ethoxy]benzyl}thiazolidin e-2,4-dione and pharmaceutically salts thereof. 14. The compound as claimed in claim 1, 5-[4-(6-hydroxy-2-isobutyl-5,7,8-trimethylchroman-2-ylmethoxy)benzyl]thiazo lidine-2,4-dione and pharmaceutically acceptable salts thereof. 15. The compound as claimed in claim 1, 5-[4-(6-acetoxy-2,5,7,8-tetramethylchroman-2-ylmethoxy)benzyl]thiazolidine- 2,4-dione and pharmaceutically acceptable salts thereof. 16. The compound as claimed in claim 1, 5-[4-(6-butyryloxy-2,5,7,8-tetramethylchroman-2-ylmethoxy)benzyl]thiazolidi ne-2,4-dione and pharmaceutically acceptable salts thereof. 17. The compound as claimed in claim 1, 5-[4-(6-hydroxy-2,5,7,8-tetramethyl-4-oxochroman-2-ylmethoxy)benzyl]thiazol idine-2,4-dione and pharmaceutically acceptable salts thereof. 18. The compound as claimed in claim 1, 5-[4-(7-t-butyl-6-hydroxy-2-methyl-4-oxochroman-2-ylmethoxy)benzyl]thiazoli dine-2,4-dione and pharmaceutically acceptable salts thereof. 19. Compounds of formula (1a): ##STR20## in which: R.sup.1 and R.sup.2 are the same or different and each represents hydrogen or a C.sub.1 -C.sub.5 alkyl group; R.sup.3 represents hydrogen; C.sub.1 -C.sub.6 aliphatic acyl; (C.sub.5 -C.sub.7 cycloalkane)carbonyl; benzoyl, benzoyl substituted with one to three substitutents selected from the group of C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, hydroxy, halogen, nitro, amino and di(C.sub.1 -C.sub.4 alkyl)amino; naphthoyl; 4-7 membered heterocyclic acyl wherein heterocyclic moiety has O, S or N hetero atoms; phenyl(C.sub.2 -C.sub.3)aliphatic acyl; cinnamoyl; (C.sub.1 -C.sub.6 alkoxy)carbonyl; or benzoyloxycarbonyl; R.sup.4 and R.sup.5 are the same or different and each represents hydrogen, a C.sub.1 -C.sub.5 alkyl group or a C.sub.1 -C.sub.5 alkoxy group, or R.sup.4 and R.sup.5 together represent a C.sub.1 -C.sub.4 alkylenedioxy group; n is 1, 2 or 3; and Y and Z are the same or different and each represents the oxygen atom or the imino group; and pharmaceutically acceptable salts thereof. 20. Compounds of formula (Ib): ##STR21## in which: R.sup.1 and R.sup.2 are the same or different and each represents hydrogen or a C.sub.1 -C.sub.5 alkyl group; R.sup.3 represents hydrogen; C.sub.1 -C.sub.6 aliphatic acyl; (C.sub.5 -C.sub.7 cycloalkane)carbonyl; benzoyl, benzoyl substituted with one to three substituents selected from the group of C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, hydroxy, halogen, nitro, amino and di(C.sub.1 -C.sub.4 alkyl)amino; naphthoyl; 4-7 membered heterocyclic acyl wherein heterocyclic moiety has O, S or N hetero atoms; phenyl(C.sub.2 -C.sub.3)aliphatic acyl; cinnamoyl; (C.sub.1 -C.sub.6 alkoxy)carbonyl; or benzoyloxycarbonyl; R.sup.4 and R.sup.5 are the same or different and each represents hydrogen, a C.sub.1 -C.sub.5 alkyl group or a C.sub.1 -C.sub.5 alkoxy group, or R.sup.4 and R.sup.5 together represent a C.sub.1 -C.sub.4 alkylenedioxy group; n is 1, 2 or 3; and Y and Z are the same or different and each represents the oxygen atom or the imino group; and pharmaceutically acceptable salts thereof. 21. Compounds of formula (Ic): ##STR22## in which: R.sup.1 and R.sup.2 are the same or different and each represents hydrogen or a C.sub.1 -C.sub.5 alkyl group; R.sup.3 represents hydrogen; C.sub.1 -C.sub.6 aliphatic acyl; (C.sub.5 -C.sub.7 cycloalkane)carbonyl; benzoyl, benzoyl substituted with one to three substituents selected from the group of C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, hydroxy, halogen, nitro, amino and di(C.sub.1 -C.sub.4 alkyl)amino; naphthoyl; 4-7 membered heterocyclic acyl wherein heterocyclic moiety has O, S or N hetero atoms; phenyl(C.sub.2 -C.sub.3)aliphatic acyl; cinnamoyl; (C.sub.1 -C.sub.6 alkoxy)carbonyl; or benzoyloxycarbonyl; R.sup.4 and R.sup.5 are the same or different and each represents hydrogen, a C.sub.1 -C.sub.5 alkyl group or a C.sub.1 -C.sub.5 alkoxy group, or R.sup.4 and R.sup.5 together represent a C.sub.1 -C.sub.4 alkylenedioxy group; n is 1, 2 or 3; R.sup.6 represents any one of the atoms or groups defined for R.sup.3 and may be the same as or different from R.sup.3 ; and Y and Z are the same or different and each represents the oxygen atom or the imino group; and pharmaceutically acceptable salts thereof. 22. Compounds as claimed in claim 1 or claim 19, which are salts with cations. 23. Compounds as claimed in claim 1 or claim 19, in the form of the sodium salt. 24. A pharmaceutical composition for the treatment of hyperlipaemia or hyperglycaemia, which comprises at least one active compound in admixture with a pharmaceutically acceptable carrier or diluent, wherein said active compound is selected from compounds of formula (I): ##STR23## in which: R.sup.1 and R.sup.2 are the same or different and each represents hydrogen or a C.sub.1 -C.sub.5 alkyl group; R.sup.3 represents hydrogen; C.sub.1 -C.sub.6 aliphatic acyl; (C.sub.5 -C.sub.7 cycloalkane)carbonyl; benzoyl, benzoyl substituted with one to three substituents selected from the group of C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, hydroxy, halogen, nitro, amino and di(C.sub.1 -C.sub.4 alkyl)amino; naphthoyl; 4-7 membered heterocyclic acyl wherein heterocyclic moiety has O, S or N hetero atoms; phenyl(C.sub.2 -C.sub.3)aliphatic acyl; cinnamoyl; (C.sub.1 -C.sub.6 alkoxy)carbonyl; or benzoyloxycarbonyl; R.sup.4 and R.sup.5 are the same or different and each represents hydrogen, a C.sub.1 -C.sub.5 alkyl group or a C.sub.1 -C.sub.5 alkoxy group, or R.sup.4 and R.sup.5 together represent a C.sub.1 -C.sub.4 alkylenedioxy group; n is 1, 2 or 3; W represents the --CH.sub.2 --, >CO or >CH--OR.sup.6 group (in which R.sup.6 represents any one of the atoms or groups defined for R.sup.3 and may be the same as or different from R.sup.3); and Y and Z are the same or different and each represents the oxygen atom or the imino group; and pharmaceutically acceptable salts thereof. 25. Compositions as claimed in claim 24, in which: R.sup.3 represents hydrogen, a C.sub.1 -C.sub.6 aliphatic acyl group, one of said aromatic acyl groups or one of said heterocyclic acyl groups. 26. Compositions as claimed in claim 24, in which: Y represents an oxygen atom; R.sup.1 and R.sup.2 are the same or different and each represents hydrogen or a C.sub.1 -C.sub.5 alkyl group; R.sup.3 represents hydrogen, a C.sub.1 -C.sub.6 aliphatic acyl group, one of said aromatic acyl groups or a pyridinecarbonyl group; and R.sup.4 and R.sup.5 are the same or different and each represents hydrogen, a C.sub.1 -C.sub.5 alkyl group or a C.sub.1 or C.sub.2 alkoxy group. 27. Compositions as claimed in claim 26, in which: R.sup.1, R.sup.2, R.sup.4 and R.sup.5 are the same or different and each represents hydrogen or a C.sub.1 -C.sub.5 alkyl group; n is 1 or 2; and W represents the --CH.sub.2 -- or >CO group. 28. Compositions as claimed in claim 27, in which R.sup.3 represents a hydrogen atom, a C.sub.1 -C.sub.5 aliphatic acyl group, or the benzoyl or nicotinoyl group. 29. Compositions as claimed in claim 28, in which: R.sup.1 and R.sup.4 are the same or different and each represents a C.sub.1 -C.sub.5 alkyl group; R.sup.2 and R.sup.5 are the same or different and each represents the hydrogen atom or the methyl group; and R.sup.3 represents hydrogen or a C.sub.1 -C.sub.4 aliphatic acyl group. 30. Compositions as claimed in claim 24, in which: W represents the --CH.sub.2 -- or >CO group; Y and Z both represent oxygen atoms; n is 1 or 2; R.sup.1 and R.sup.4 are the same or different and each represents a C.sub.1 -C.sub.4 alkyl group; R.sup.2 and R.sup.5 are the same or different and each represents the hydrogen atom or the methyl group; and R.sup.3 represents hydrogen or a C.sub.1 -C.sub.4 aliphatic acyl group. 31. Compositions as claimed in claim 30, in which n is 1. 32. Compositions as claimed in claim 30 or claim 17, in which W represents the --CH.sub.2 -- group. 33. Compositions as claimed in claim 24, wherein said active compound is selected from the group consisting of: 5-[4-(6-hydroxy-2,5,7,8-tetramethylchroman-2-ylmethoxy)benzyl]thiazolidine- 2,4-dione 5-[4-(2-ethyl-6-hydroxy-5,7,8-trimethylchroman-2-ylmethoxy)benzyl]thiazolid ine-2,4-dione 5-[4-(6-hydroxy-5,7,8-trimethylchroman-2-ylmethoxy)benzyl]thiazolidine-2,4- dione 5-{4-[2-(6-hydroxy-2,5,7,8-tetramethylchroman-2-yl)ethoxy]benzyl}thiazolidi ne-2,4-dione 5-{4-[2-(7-t-butyl-6-hydroxy-2-methylchroman-2-yl)ethoxy]benzyl}thiazolidin e-2,4-dione 5-{4-[2-(6-hydroxy-7,8-dimethoxy-2,5-dimethylchroman-2-yl)ethoxy]benzyl}thi azolidine-2,4-dione 5-[4-(6-hydroxy-2,7-dimethylchroman-2-ylmethoxy)benzyl]thiazolidine-2,4-dio ne 5-[4-(6-hydroxy-2-isobutyl-5,7,8-trimethylchroman-2-ylmethoxy)benzyl]thiazo lidine-2,4-dione 5-[4-(6-hydroxy-2,5,7,8-tetramethylchroman-2-ylmethoxy)benzyl]-2-iminothiaz olidin-4-one 5-[4-(7-t-butyl-6-hydroxy-2-methylchroman-2-ylmethoxy)benzyl]-2-iminothiazo lidin-4-one 5-[4-(2-ethyl-6-hydroxy-5,7,8-trimethylchroman-2-ylmethoxy)benzyl]-2-iminot hiazolidin-4-one 5-[4-(6-hydroxy-5,7,8-trimethylchroman-2-ylmethoxy)benzyl]-2-iminothiazolid in-4-one 5-[4-(6-hydroxy-2,7-dimethylchroman-2-ylmethoxy)benzyl]-2-iminothiazolidin- 4-one 5-[4-(6-acetoxy-2,5,7,8-tetramethylchroman-2-ylmethoxy)benzyl]thiazolidine- 2,4-dione 5-[4-(6-benzoyloxy-2,5,7,8-tetramethylchroman-2-ylmethoxy)benzyl]thiazolidi ne-2,4-dione 5-[4-(6-butyryloxy-2,5,7,8-tetramethylchroman-2-ylmethoxy)benzyl]thiazolidi ne-2,4-dione 5-[4-(2,5,7,8-tetramethyl-6-nicotinoyloxychroman-2-ylmethoxy)benzyl]thiazol idine-2,4-dione 5-[4-(6-hydroxy-2,5,7,8-tetramethyl-4-oxochroman-2-ylmethoxy)benzyl]thiazol idine-2,4-dione 5-[4-(7-t-butyl-6-hydroxy-2-methyl-4-oxochroman-2-ylmethoxy)benzyl]thiazoli dine-2,4-dione 5-[4-(6-hydroxy-2-isobutyl-5,7,8-trimethyl-4-oxochroman-2-ylmethoxy)benzyl] thiazolidine-2,4-dione 5-[4-(6-hydroxy-2,5,7,8-tetramethyl-4-oxochroman-2-ylmethoxy)benzyl]-2-imin othiazolidin-4-one 5-[4-(7-t-butyl-6-hydroxy-2-methyl-4-oxochroman-2-ylmethoxy)benzyl]-2-imino thiazolidin-4-one 5-[4-(6-hydroxy-2-isobutyl-5,7,8-trimethyl-4-oxochroman-2-ylmethoxy)benzyl] -2-iminothiazolidin-4-one 5-[4-(6-acetoxy-2,5,7,8-tetramethyl-4-oxochroman-2-ylmethoxy)benzyl]thiazol idine-2,4-dione 5-[4-(6-acetoxy-5,7,8-trimethylchroman-2-ylmethoxy)benzyl]-2-iminothiazolid in-4-one 5-{4-[2-(6-acetoxy-7-t-butyl-2-methylchroman-2-yl)ethoxy]benzyl}-2-iminothi azolidin-4-one 5-{4-[2-(6-actoxy-7,8-dimethoxy-2,5-dimethylchroman-2-yl)ethoxy]benzyl}-2-i minothiazolidin-4-one and pharmaceutically acceptable salts thereof. 34. Compositions as claimed in claim 24, wherein said active compound is selected from the group consisting of: 5-[4-(6-hydroxy-2,5,7,8-tetramethylchroman-2-ylmethoxy)benzyl]thiazolidine- 2,4-dione 5-[4-(2-ethyl-6-hydroxy-5,7,8-trimethylchroman-2-ylmethoxy)benzyl]thiazolid ine-2,4-dione 5-{4-[2-(7-t-butyl-6-hydroxy-2-methylchroman-2-yl)ethoxy]benzyl}thiazolidin e-2,4-dione 5-[4-(6-hydroxy-2-isobutyl-5,7,8-trimethylchroman-2-ylmethoxy)benzyl]thiazo lidine-2,4-dione 5-[4-(6-acetoxy-2,5,7,8-tetramethylchroman-2-ylmethoxy)benzyl]thiazolidine- 2,4-dione 5-[4-(6-butyryloxy-2,5,7,8-tetramethylchroman-2-ylmethoxy)benzyl]thiazolidi ne-2,4-dione 5-[4-(6-hydroxy-2,5,7,8-tetramethyl-4-oxochroman-2-ylmethoxy)benzyl]thiazol idine-2,4-dione 5-[4-(7-t-butyl-6-hydroxy-2-methyl-4-oxochroman-2-ylmethoxy)benzyl]thiazoli dine-2,4-dione and pharmaceutically acceptable salts thereof. 35. Compositions as claimed in claim 24, in which said active compound is selected from compounds of formula (1a): ##STR24## in which: R.sup.1 and R.sup.2 are the same or different and each represents hydrogen or a C.sub.1 -C.sub.5 alkyl group; R.sup.3 represents hydrogen; C.sub.1 -C.sub.6 aliphatic acyl; (C.sub.5 -C.sub.7 cycloalkane)carbonyl; benzoyl, benzoyl substituted with one to three substituents selected from the group of C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, hydroxy, halogen, nitro, amino and di(C.sub.1 -C.sub.4 alkyl)amino; naphthoyl; 4-7 membered heterocyclic acyl wherein heterocyclic moiety has O, S or N hetero atoms; phenyl(C.sub.2 -C.sub.3)aliphatic acyl; cinnamoyl; (C.sub.1 -C.sub.6 alkoxy)carbonyl; or benzoyloxycarbonyl; R.sup.4 and R.sup.5 are the same or different and each represents hydrogen, a C.sub.1 -C.sub.5 alkyl group or a C.sub.1 -C.sub.5 alkoxy group, or R.sup.4 and R.sup.5 together represent a C.sub.1 -C.sub.4 alkylenedioxy group; n is 1, 2 or 3; and Y and Z are the same or different and each represents the oxygen atom or the imino group; and pharmaceutically acceptable salts thereof. 36. Compositions as claimed in claim 24, in which said active compound is selected from compounds of formula (Ib): ##STR25## in which: R.sup.1 and R.sup.2 are the same or different and each represents hydrogen or a C.sub.1 -C.sub.5 alkyl group; R.sup.3 represents hydrogen; C.sub.1 -C.sub.6 aliphatic acyl; (C.sub.5 -C.sub.7 cycloalkane)carbonyl; benzoyl, benzoyl substituted with one to three substituents selected from the group of C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, hydroxy, halogen, nitro, amino and di(C.sub.1 -C.sub.4 alkyl)amino; naphthoyl; 4-7 membered heterocyclic acyl wherein heterocyclic moiety has O, S or N hetero atoms; phenyl(C.sub.2 -C.sub.3)aliphatic acyl; cinnamoyl; (C.sub.1 -C.sub.6 alkoxy)carbonyl; or benzoyloxycarbonyl; R.sup.4 and R.sup.5 are the same or different and each represent hydrogen, a C.sub.1 -C.sub.5 alkyl group or a C.sub.1 -C.sub.5 alkoxy group, or R.sup.4 and R.sup.5 together represent a C.sub.1 -C.sub.4 alkylenedioxy group; n is 1, 2 or 3; and Y and Z are the same or different and each represents the oxygen atom or the amino group; and pharmaceutically acceptable salts thereof. 37. Compositions as claimed in claim 24, in which said active compound is selected from compounds of formula (Ic): ##STR26## in which: R.sup.1 and R.sup.2 are the same or different and each represents hydrogen or a C.sub.1 -C.sub.5 alkyl group; R.sup.3 represents hydrogen; C.sub.1 -C.sub.6 aliphatic acyl; (C.sub.5 -C.sub.7 cycloalkane)carbonyl; benzoyl, benzoyl substituted with one to three substituents selected from the group of C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, hydroxy, halogen, nitro, amino and di(C.sub.1 -C.sub.4 alkyl)amino; naphthoyl; 4-7 membered heterocyclic acyl wherein heterocyclic moiety has O, S or N hetero atoms; phenyl(C.sub.2 -C.sub.3)aliphatic acyl; cinnamoyl; (C.sub.1 -C.sub.6 alkoxy)carbonyl; or benzoyloxycarbonyl; R.sup.4 and R.sup.5 are the same or different and each represents hydrogen, a C.sub.1 -C.sub.5 alkyl group or a C.sub.1 -C.sub.5 alkoxy group, or R.sup.4 and R.sup.5 together represent a C.sub.1 -C.sub.4 alkylenedioxy group; n is 1, 2 or 3; R.sup.6 represents any one of the atoms or groups defined for R.sup.3 and may be the same as or different from R.sup.3 ; and Y and Z are the same or different and each represents the oxygen atom or the imino group; and pharmaceutically acceptable salts thereof. 38. Compositions as claimed in claim 24 or claim 35, wherein said active compound is in the form of a salt with a cation. 39. Compositions as claimed in claim 24 or claim 35, wherein said active compound is in the form of the sodium salt.