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.
Aromatic [5,5]-rearrangement can in principle be an ideal protocol to access dearomative compounds. However, the lack of competent [5,5]-rearrangement impedes the advance of the protocol. In this Article, we showcase the power of [5,5]-rearrangement recently developed in our laboratory for constructing an intriguing dearomative sulfonium specie which features versatile and unique reactivities to perform nucleophilic 1,2- and 1,4-addition and cyclization, thus achieving dearomative di- and trifunctionalization of easily accessible aryl sulfoxides. Impressively, the dearomatization products can be readily converted to sulfur-removed cyclohexenones, naphthalenones, bicyclic cyclohexadienones, and multi-substituted benzenes. Mechanistic studies shed light on the key intermediates and the remarkable chemo-, regio- and stereoselectivities of the reactions.
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.
Herein we report the ortho‐cyanoalkylation of aryl fluoroalkyl sulfoxides with alkyl nitriles. The reaction proceeds through an “assembly/deprotonation” triggered [3,3]‐rearrangement and allows the incorporation of two valuable functional groups including the cyano group and difluoromethylthio group into arenes. As a consequence, a wide range of ortho‐cyanoalkylated difluoromethylthio arenes were produced with high efficiency under mild and environmentally friendly conditions. Remarkably, the reaction proceeds smoothly with the electron‐donating group substituted arenes which can be challenging to the reaction of non‐fluoroalkyl sulfoxides. This beneficial effect can be attributed to the unique electronegativity of fluoroalkyl substituents.
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