The multicomponent reaction (MCR) of aromatic aldehydes 1 and malononitrile (2) with active methylenes 5a–h in the presence of L-proline produced pyrans and thiopyrans 6a–h stereospecifically and in good yields. Moreover a novel MCR of ethyl propiolate (8) with 1 and 2 in the presence of L-proline to afford (R)-polysubstituted pyran is also reported. X-ray structures, e.e. and optical activity of the synthesized compounds indicated that L-proline as a catalyst is responsible for the observed enantioselectivity in the studied reactions.

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The role of glycerol as a green bio-based solvent, reactant, and/or a catalyst in the synthesis of novel heterocycles, under pressure, is studied. Synthesis of novel quinolines in good yields using a new modified Skraup synthesis, utilizing glycerol and pressure Q-tubes, is demonstrated. Novel aniline trimers are prepared using glycerol, and substituted anilines under pressure, in acidic medium and water. Glycerol was employed as a catalyst and a green solvent in the synthesis of novel pyridazines 13a–c. The mechanisms of the reactions and the catalytic effect of glycerol in protic and aprotic media are fully discussed. The structures of the synthesized compounds were determined via X-ray crystallography and spectroscopic methods.

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