Regioselective synthesis of substituted thiazoles via cascade reactions from 3-chlorochromones and thioamides.

A facile and efficient strategy to synthesize substituted thiazoles via a cascade reaction from chromone derivatives and thioamides in an environmentally benign medium was developed. This cascade reaction involves a Michael addition/intramolecular cyclization process and a broad scope of reversed regioselectivity products was prepared in a short reaction time with excellent yields. The reversed regioselectivity was also explained by DFT calculations.