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 (FT128;IR) and ¹H and ¹³C 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.