Synthesis of some new azole, pyrimidine, pyran, and benzo/naphtho[ b ]furan derivatives incorporating thiazolo[3,2‐ a ]benzimidazole moiety

Reaction of E ‐3‐( N , N ‐dimethylamino)‐1‐(3‐methylthiazolo[3,2‐ a ]benzimidazol‐2‐yl)prop‐2‐en‐1‐one ( 1 ) with some N ‐nucleophiles, such as anilines 2a , 2b , 2c , 4‐amino‐ N ‐pyridin‐2‐yl‐benzenesulfonamide ( 4a ), 4‐amino‐ N ‐pyrimidin‐2‐yl‐benzenesulfonamide ( 4b ), hydrazine, hydroxylamine, thiourea, and guanidine afforded the corresponding arylaminoprop‐2‐en‐1‐one derivatives 3a , 3b , 3c , 5a , 5b , the pyrazole, isoxazole, pyrimidinethione and aminopyrimidine derivatives 7a , 7b , 9a , and 9b , respectively. The utility of compound 1 , as a versatile building block, for the synthesis of the pyranone 13 , benzo[ b ]furan 17a , and naphtho[1,2‐ b ]furan 17b was also explored via its reaction with 2‐benzamidoacetic acid ( 10 ), 1,4‐benzoquinone ( 14a ), and 1,4‐naphthoquinone ( 14b ), respectively. J. Heterocyclic Chem., (2011).