Microwave promoted synthesis of 4,5-dihydrofurans via three-component reaction in solvent-free conditions

Dihydrofurans are the most important heterocycles commonly found in a wide range of biologically active synthetic and natural products [1]. The development ofresource and ecofriendly process in termsof sustainable chemistry for their synthesis remains an area of current interest, and various synthetic methods have been reported in literature. The use of microwave for the synthesis of organic compounds under solvent-free conditions proved to be efficient, safe and environmentally benign technique, with shorter reaction time, high yield, and easier work-up [2]. In continuation of our research on the development of new methodologies for synthesis of heterocyclic compounds and use of green chemical techniques [3], we herein disclose microwave assisted synthesis of 4,5-dihydrofurans 4 in good yields by three-component reaction of 3-(cyanoacetyl)indole1 with aromatic aldehydes 2 and N-phenacylpyridinium bromide 3 under solvent-free conditions (Figure 1).The structure of products is characterized on the basis of their elemental analysis, 1H NMR and 13C NMR, IR and mass spectra.