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 (Tf2O) 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 Tf2O 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.
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 (Tf2O) 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 Tf2O 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.
We report a simple protocol for (ethoxycarbonyl)difluoromethylthiolation of nucleophilic compounds using a difluoroalkyl sulfonium salt which can be in situ prepared via Tf2O triggered electrophilic activation of a benzyl difluoroalkyl sulfoxide. With the protocol, difluoroalkylthiolated arenes, heteroarenes and α-difluoroalkylthiolated carbonyl compounds etc. were obtained smoothly with good to excellent yields. Merits of the reaction include the readily available difluoroalkylthiolation reagent and substrates, mild conditions, and excellent regioselectivity.
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