Solvent free l-proline-catalysed domino Knoevenagel/6π-electrocyclization for the synthesis of highly functionalised 2H-pyrans

Abstract

An environmentally benign synthesis of 2H-pyrans has been achieved in high yield using β-oxosulfones and 3,3-dialkylsubstituted α,β-unsaturated aldehydes. The key reaction is a solvent free L-proline catalysed domino Knoevenagel/6π-electrocyclization. As 3,3-dialkylsubstituted α,β-unsaturated aldehydes are a very common feature in many natural products, the transformation into highly functionalised 2H-pyrans makes this procedure a green and excellent method for a diversity oriented synthesis of biologically active compounds.