Reaction of 3-iodochromone with nucleophiles 2. Reaction with mercaptoazoles

3-Iodochromone (1a) easily reacted with mercaptoazoles in the presence of p otassium carbonate to give 3-azolylthiochromones in good yields. In the cas e of 2-mercaptobenzimidazole (2a) as a nucleophile, the benzimidazo[2,1-b]t hiazole derivative (4a) was obtained as the major product along with 3-(1H- benzimidazol-2-ylthio)chromone (3a). The ratio of the two products was foun d to be affected by the electron density on the nitrogen atom in the benzim idazole ring.