Morita-Baylis-Hillman-type [3,3]-Rearrangement Reaction Of Aryl Sulfoxide

The[3,3]-rearrangement is an important reaction pattern for synthetic chemistry.Traditional research on this topic emphasizes on seeking new reaction conditions to promote the rearrangement of a relatively stable rearrangement precursor.In the past few years,the[3,3]-rearrangement of aryl sulfoxides with certain nucleophiles via the construction of unstable rearrangement precursors has been greatly advanced.This type of reaction proceeds under catalyst-and metal-free conditions and has become a powerful synthetic tool.Recently,our group developed the[3,3]-rearrangement of aryl sulfoxides with alkyl nitriles via the assembly of unstable imine sulfonium species from two coupling partners and the subsequent deprotonation.With the newly developed“assembly/deprotonation”protocol,we have also realized a selective[5,5]-rearrangement of aryl sulfoxides with allyl nitriles.The“assembly/deprotonation”strategy dividing the traditional one-step rearrangement reaction into two steps enables the more precise control of the reaction that is essential for the development of aryl sulfoxide-rearrangement reactions.As such,in this thesis,we describe a new strategy namely the“assembly/addition”for triggering the rearrangement of aryl sulfoxides with?,?-unsaturated nitriles.Specifically,Tf₂O initiates the electrophilic assembly of both coupling partners,providing an unstable?,?-unsaturated imine sulfonium intermediate.The subsequent Morita-Baylis-Hillman?MBH?-type addition forms a ketenimine sulfonium species that can readily undergo[3,3]-rearrangement and?-elimination to?-arylated?,?-unsaturated nitriles.The reaction features mild conditions,excellent functional group compatibility,and broad substrate scope.Notably,a remarkable Z-selectivity was also observed.This unusual stereoselectivity is rare in the field of the related MBH reaction.