A Stereocontrolled Cyclopentenone Synthesis via Cycloaddition

Article abstract of DOI:10.1021/ja00201a032

γ-Alkoxy-α,β-unsaturated sulfones are readily available in both racemic and scalemic form, the latter either by asymmetric induction from achiral building block or from readily available scalemic starting materials.These electron deficient olefins serve as excellent substrates for <3+2> cycloaddition involving the intermediacy of trimethylenemethane-palladium complexes.The highly diastereoselective methylenecyclopentannulation provides a versatile cycloadduct that allows very simple conversion to cyclopentenones and cyclopentadienes and the synthetic equivalent ofaddition to cycloalkanones and alkynones, two classes of substrate that either frequently give low yields or totally fail in palladium-catalyzed cycloadditions from 2-(acetoxymethyl)-3-(trimethylsilyl)prop-1-ene.