Stereoselective 1,6-Conjugate Addition/Annulation of <i>para</i>-Quinone Methides with Vinyl Epoxides/Cyclopropanes

Here, we present an unprecedented formal [3 + 2] cycloaddition of para-quinone methides with vinyl epoxides/cyclopropanes to deliver a wide range of spiro[4.5]­decanes in high efficiency and stereoselectivity. The commercial availability of the catalysts and reagents, together with the convenient procedure, makes it an attractive method in asymmetric synthesis.