Solid state synthesis of 2-aroylbenzo[b]furans, 1,3-thiazoles and 3-aryl-5,6-dihydroimidazo[2,1-b][1,3]thiazoles from α-tosyloxyketones using microwave irradiation †

Abstract

The expeditious solventless syntheses of 2-aroylbenzo[b]furans, 1,3-thiazoles and 3-aryl-5,6-dihydroimidazo[2,1-b][1,3]thiazoles are described from readily accessible α-tosyloxyketones and mineral oxides in processes that are accelerated by exposure to microwaves. The 2-aroylbenzo[b]furans are readily obtained from salicylaldehydes and α-tosyloxyketones in the presence of solid potassium fluoride doped alumina (KF–Al₂O₃) whereas montmorillonite K-10 clay provides 1,3-thiazoles from thioamides and α-tosyloxyketones. Similarly, ethylenethiourea and α-tosyloxyketones provide bridgehead nitrogen heterocycles, 3-aryl-5,6-dihydroimidazo[2,1-b][1,3]thiazoles, in excellent yields which are not easily obtainable under classical heating conditions.