Synthesis, stereochemistry and biological activity of some novel long alkyl chain substituted thiazolidin-4-ones and thiazan-4-one from 10-undecenoic acid hydrazide

The synthesis of four novel compounds, (i) [(11-{[2-(3-nitrophenyl)-4-oxo-1,3-thiazolidin-3-yl]amino}-11-oxoundecyl)sulfanyl]acetic acid (4), (ii) N-[5-methyl-2-(3-nitrophenyl)-4-oxo-1,3-thiazolidin-3-yl]undec-10-enamide (5), (iii) 2-[(11-{[5-methyl-2-(3-nitrophenyl)-4-oxo-1,3-thiazolidin-3-yl]amino}-11-oxoundecyl)sulfanyl]propanoic acid (6) and (iv) 3-[(11-{[2-(3-nitrophenyl)-4-oxo-1,3-thiazinan-3-yl]amino}-11-oxoundecenyl) sulfanyl]propanoic acid (8) from 10-undecenoic acid hydrazide (1) via m-nitrobenzaldehyde-10-undecenohydrazone (2) using mercaptoacetic acid in (i), 2-mercaptopropionic acid in (ii and iii) and 3-mercaptopropionic acid in (iv) is described. The uncyclized products, ({11-[(2E)-2-(3-nitrobenzylidene)hydrazino]-11-oxo-undecyl}sulfanyl)acetic acid (3) and 3-({11-[(2E)-2-(3-nitrobenzylidene)hydrazino]-11-oxoundecyl}sulfanyl)propanoic acid (7) are also obtained in (i) and (iv), respectively. The hydrazones (2), (3) and (7) exist in two conformers as synperiplanar and antiperiplanar. Structural assignment, stereochemistry and biological assays are discussed.