1-Ethyl-3-Methylimidazolium Cyanoborohydride Catalyzed Solvent Free Microwave Assisted One Pot Multicomponent Synthesis of Tetrahydrobenzo[b]Pyran Derivatives

We present a facile and environmentally benign protocol for the synthesis of tetrahydrobenzo[b]pyran derivatives via multicomponent condensation of dimedon, malononitrile and different aromatic aldehydes in the presence of 1-ethyl-3-methylimidazolium cyanoborohydride ([EMIm][BH3CN]) as catalyst under microwave irradiation. The one-pot synthesis, facile solvent-free condition and good isolated yield illustrate the utility of this green approach. The structural features are derived using analytical tools, including Fourier Transform Infrared Spectroscopy (FT-IR) and H-1 and C-13 Nuclear Magnetic Resonance (NMR) Spectroscopy. Electronic synthesis of tetrahydrobenzo[b]pyran derivatives by using catalytic action of 1-ethyl-3-methylimidazolium cyanoborohydride has been used to obtain maximum yield.

Automated summary

A facile and environmentally friendly method was developed for the synthesis of tetrahydrobenzo[b]pyran derivatives via multicomponent condensation reaction using 1-ethyl-3-methylimidazolium cyanoborohydride as the catalyst under microwave irradiation. This green approach offers the advantages of one-pot synthesis, solvent-free condition, and good yield.