Z ‐Selective α‐Arylation of α,β‐Unsaturated Nitriles via [3,3]‐Sigmatropic Rearrangement

The Morita‐Baylis–Hillman (MBH) reaction and [3, 3]‐sigmatropic rearrangement are two paradigms in organic synthesis. We have merged the two types of reactions to achieve [3,3]‐rearrangement of aryl sulfoxides with α,β‐unsaturated nitriles. The reaction was achieved by sequentially treating both coupling partners with electrophilic activator (Tf 2 O) and base, offering an effective approach to prepare synthetically versatile α‐aryl α,β‐unsaturated nitriles with Z ‐selectivity through direct α‐C‐H arylation of unmodified α,β‐unsaturated nitriles. The control experiments and DFT calculations support a four‐stage reaction sequence, including the assembly of Tf 2 O activated aryl sulfoxide with α,β‐unsaturated nitrile, MBH‐like Lewis base addition, [3,3]‐rearrangement, and E1cB‐elimination. Among these stages, the Lewis base addition is diastereoselective and E1cB‐elimination is cis ‐selective, which could account for the remarkable Z ‐selectivity of the reaction.