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

The reaction of (2E,4E)-5-phenyl-2-cyano-2,4-pentadienethioamide or (E)-3-(2-nitrophenyl)acrolein and cyanothioacetamide with α-bromoketones afforded new (2E,4E)-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 C5 position of the thiazole ring without affecting the diene system and leads to the formation of new series of (2E,4E)-5-aryl-2-(5-bromo-4-arylthiazol-2-yl)penta-2,4-dienenitriles.