Síntese de benzotiazóis 2-substituídos utilizando α-cetoácidos e Na2S2O5

Abstract

In this work, it has been developed a new methodology to synthesize 2-substituted benzothiazoles from α-keto acids and bis(2-aminophenyl)disulfide, using the Na2S2O5/DMSO system. The protocol is simple and neither inert atmosphere nor anhydrous media are necessary. By this procedure, several differently substituted benzothiazoles were prepared starting from commercially available reagents. This methodology consists in simply stirring the reagents in a vessel at 100 oC for 1-4 h, giving the desired products in good to excellent yields. This is an efficient and versatile alternative to 2-substituted benzothiazoles, which is not sensible to electronic effects in the phenylglyoxylic acid. Additionally, the use of disulfide as starting material, which is more stable and easy to manipulate than thiols, is another advantage of this new approach.