Synthesis of 2‐Substituted 1,3‐Benzoselenazoles from Carboxylic Acids Promoted by Tributylphosphine

Abstract We report a general, practical, and simple metal‐free method for the synthesis of 2‐substituted 1,3‐benzoselenazoles by the reaction of bis(2‐aminophenyl)diselenide with a wide range of carboxylic acids, promoted by tributylphosphine. This efficient reaction furnishes 2‐aryl‐1,3‐benzoselenazoles in good yields and tolerates a variety of substituents at the aryl moiety of carboxylic acids. For the first time, 2‐alkyl‐1,3‐benzoselenazoles could be obtained from aliphatic carboxylic acids and thiazolidine‐4‐carboxylic acid in high chemical yields. The use of focused microwave irradiation considerably decreased the reaction time from 48 to 2 h. The experimental data provide insights into the mechanism of the reaction.