Synthesis and Regiospecific Bromination of (2E,4E)-5-Aryl-2-(4-arylthiazol-2-yl)penta-2,4-dienenitrile

The reaction of (2 E ,4 E )-5-phenyl-2-cyano-2,4-pentadienethioamide or ( E )-3-(2-nitrophenyl)acrolein and cyanothioacetamide with α-bromoketones afforded new (2 E ,4 E )-5-aryl-2-(4-arylthiazol-2-yl)penta-2,4-dienenitriles. Direct bromination of the latter by the action of bromine in DMF proceeded regiospecifically at the C 5 position of the thiazole ring without affecting the diene system and leads to the formation of new series of (2 E ,4 E )-5-aryl-2-(5-bromo-4-arylthiazol-2-yl)penta-2,4-dienenitriles.