Synthesis of some novel pyrazolo[1,5‐a]pyrimidine, 1,2,4‐triazolo[1,5‐a]pyrimidine, pyrido[2,3‐d]pyrimidine, pyrazolo[5,1‐c]‐1,2,4‐triazine and 1,2,4‐triazolo[5,1‐c]‐1,2,4‐triazine derivatives incorporating a thiazolo[3,2‐a]benzimidazole moiety

Abstract magnified image E‐3‐(N,N‐Dimethylamino)‐1‐(3‐methylthiazolo[3,2‐a]benzimidazol‐2‐yl)prop‐2‐en‐1‐one (2) was synthesized by the reaction of 1‐(3‐methylthiazolo[3,2‐a]benzimidazol‐2‐yl)ethanone (1) with dimethylformamide‐dimethylacetal. The reaction of2with 5‐amino‐3‐phenyl‐1H‐pyrazole (4a) or 3‐amino‐1,2,4‐(1H)‐triazole (4b) furnished pyrazolo[1,5‐a]pyrimidine and 1,2,4‐triazolo[1,5‐a]pyrimidine derivatives6aand6b, while the reaction of enaminone2with 6‐aminopyrimidine derivatives7a,bafforded pyrido[2,3‐d]pyrimidine derivatives9a,b, respectively. The diazonium salts11aor11bcoupled with compound2to yield the pyrazolo[5,1‐c]‐1,2,4‐triazine and 1,2,4‐triazolo[5,1‐c]‐1,2,4‐triazine derivatives13aand13b. Some of the newly synthesized compounds exhibited a moderate effect against some bacterial and fungal species.