A CONVENIENT ONE-POT SYNTHESIS OF 2-BENZIMIDAZOLYL-THIOACETOPHENONES AND THIAZOLO[3,2-A]BENZIMIDAZOLES

2-Mercaptobenzimidazole (1) reacts with aromatic ketones 2a-d in acidi fied acetic acid giving 2-benzimidazolylthioacetophenones 3a-d. which on cyclization yield thiazolo[3,2-a]benzimidazoles 4a-d. Acetylation o f 3a,d gave the N-acetyl derivatives 5a,d. Cyclization of 3a-d or 5d i n acetic anhydride or acetic anhydride/pyridine mixture afforded 6a-d. While reaction of 1 with aliphatic or alicyclic ketones gave directly 2,3-disubstituted thiazolo[3.2-a]benzimidazoles 7a-f and 8a-d respect ively. Copyright (C) 1996 Elsevier Science Ltd