SYNTHESIS AND PHOTOTOXICITY OF SOME 2-[2-(2-THIENYL)THIAZOL-4-YL]-1,3,4-OXA OR THIADIAZOLES AND 3-[2-(2-THIENYL)THIAZOL-4-YL]-1,2,4-TRIAZOLIN-5-THIONES

2-Acyl-1-[2-(2-thienyl)-4-thiazolecarbonyl]hydrazines (4), obtained from 2-(2-thienyl)-4-thiazole carbohydrazide (3) and acid chlorides, were cyclized with PPA and P2S5 separately to 5-alkyl-2-[2-thienyl)thiazol-4-yl]-1,3,4-oxa and thiadiazoles (6, 7), respectively. The thiosemicarbazides (5), obtained from reaction of 3 and alkyl isothiocyanates, on cyclodehydration with I-2/NaOH and conc. H2SO4 separately furnish 5-alkylamino-2-[2-(2-thienyl)thiazol-4-yl]-1,3,4-oxa and thiadiazoles (8 and 9), respectively. Refluxing 5 in dil NaOH, however, provide 4-alkyl-[2-(2-thienyl)thiazol-4-yl]-1,2,4 5-thiones (10). The NMR (H-1 and C-13) and mass spectral characteristics of these compounds are also reported.