Mild, asymmetric Diels-Alder cycloadditions of electronically matched 2-pyrones and vinyl ethers

Abstract

Silica gel and a TADDOL-complexed titanium IV Lewis acid are shown to promote mild, practical, asymmetric [4+2]-cycloadditions of electron-poor 2-pyrone-3-carboxylates with electron-rich vinyl ethers to form isolable and useful bicyclic lactone adducts.