Efficient one-step synthesis of benzazoles in aqueous media

Abstract

Benzazoles (benzoxazoles, benzothiazoles, and benzimidazoles) were efficiently prepared by the aquatic reaction of the corresponding thioamidinium salts and 2-aminophenol, 2-aminothiophenol, and 1,2-diaminobenzene, respectively. The thioamidinium salt was successfully applied as an alternative to a carboxylic acid derivative to react smoothly with an amino precursor and in the presence of catalytic amounts of hexadecyltrimethylammonium bromide salt to produce benzazoles in good to excellent yields. © Wiley-VCH Verlag GmbH & Co. KGaA 2009.