1H-imidazo[4,5-b]pyridin-2-amine (1) reacts with ammoniumthiocyanide to
form 1-(1H-imidazo[4,5-b]pyridin-2-yl)thiourea (2), which on reaction with
chloroacetic acid gives 2-(1H-imidazo[4,5-b]pyridin-2-ylimino)thiazolidin-4-
one (3). Compound 3 on condensation gives 2-(1H-imidazo[4,5-b]pyridin-2-
ylimino)-5-arylidenethiazolidin-4-ones (4a-e). Further 1H-imidazo[4,5-
b]pyridin-2-amine (1) reacts with aromatic isothiocyanates to form compound
5 which is cyclized to 1-(1H-imidazo[4,5-b]pyridin-2-yl)-5-methyl-3-aryl-1,3,5-
triazinane-2-thiones (6a-e) and 3-(1H-imidazo[4,5-b]pyridin-2-yl)-5-aryl-1,3,5-
oxadiazinane-4-thiones (7a-e).
Keywords: Synthesis; Thiones; Heterocycles