Abstract

Diversity oriented synthetic protocol has been presented for the synthesis of structurally diverse drug -like small molecules. The present method involves three-component domino reaction of 2- aminobenzothiazoles, thiophene-2-carbaldehyde and carbonyl compounds in the presence of a catalytic amount of p-toluenesulphonic acid (p-TSA) as a recyclable and reusable eco-friendly acid catalyst in aqueous- alcoholic medium (C₂H₅OH- H₂O:v:v/ 1:5). The synthesis of structurally diverse heterocycles in very high yields (92-97%) from easily available starting materials, operational simplicity, mild reaction conditions, use of nontoxic and reusable acid catalyst, environmentally benign solvent system and shorter reaction time (10- 48 min) at comparatively low temperature are special features of the present synthetic protocol.

Keywords: 2-aminobenzothiazoles, benzothiazolochromenopyrimidines, benzothiazolopyranopyrimidines, benzothiazolopyrimidines, benzothiazolopyrimidopyrimidines, diversity oriented synthesis, p-toluenesulphonic acid (p-TSA), sustainable chemistry.

Graphical Abstract