A robust one-pot synthesis of benzothiazoles from carboxylic acids including examples with hydroxyl and amino substituents

The cyclocondensation of 2-aminothiophenol and carboxylic acids to give benzothiazoles has been carried out under mild conditions using tetrabutylammonium bromide (TBAB) as the reaction medium and triphenyl phosphite as the catalyst. Shorter reaction times, rapid isolation of the products, and excellent yields are advantages of this method. The reaction is found to be general and quite tolerant to the nature of the substituted carboxylic acids.