Photochemical Doyle-Kirmse Reaction – a Metal-Free Route to Allenes

This report describes metal-free, blue light-induced [2,3]-sigmatropic rearrangement of sulfonium ylides generated from donor/acceptor diazoalkanes and propargyl sulfides. The reaction furnishes highly functionalized allenes from a broad range of starting materials in decent yields. Mechanistic experiments supported by the literature data suggest singlet carbenes as intermediates in this reaction.