Chemical synthesis in aqueous media using microwaves

Abstract

The development of efficient, selective and eco-friendly synthetic methods has remained a major focus of our research group. Microwave (MW) irradiation as alternative energy source in conjunction with water as reaction media has proven to be a successful 'greener' chemical approach. The N-alkylation of amines by alkyl halides that proceeds expeditiously in the presence of aqueous NaOH to deliver tertiary amines and double N-alkylation of amines and hydrazine derivatives to assemble a series of heterocyclic moieties such as N-azacycloalkanes, 4,5-dihydropyrazoles and pyrazolidines etc. will be discussed as an environmentally friendlier alternative. An efficient and clean MW-assisted synthesis of alkyl azides/thiocynates will be described by reacting alkyl halides/tosylates with alkali azides/thiocynates. The salient features of using this strategy include considerable reduction in reaction times, minimization or elimination of byproduct formation and improved tolerance for functional groups such as carbonyl, hydroxyl and esters.