Dehydrative Rearrangement Of Aryl Sulfoxides And Amides

In the past few years,the[3,3]-σrearrangement of aryl sulfoxides have attracted extensive attentions of synthetic chemists.Unlike traditional rearrangement reactions,this rearrangement reaction can be performed,without presynthesis of relatively stable rearrangement precursors,only by simply mixing electrophilically activated aryl sulfoxides with specific nucleophiles.Merits of the reaction include the simple operation,readily available materials and high selectivity.Until now,scientists have found a variety of nucleophiles,such as allyl/propargyl silane,β-dicarbonyl compounds,phenols and nitriles,are all suitable for the reaction.In order to expand the broader of the reaction,the discovery of new nucleophilic rearrangement partners and development of new rearrangement patterns are still the central themes of the field.Inspired by the great advances of aryl sulfoxides involved sulfonium-rearrangement reactions,our research group has recently developed another sulfonium salt based rearrangement,namely dehydrative rearrangement of aryl sulfimines.The reaction proceeds via sequential electrophilic activation and base deprotonation of substrate to construct ketenimine sulfonium salts which undergoes[3,3]-σrearrangement to give product.On the other hand,the synthesis of sulfimines via dehydrative cross coupling of aryl sulfoxides with amides in presence of electrophilic reagents and organic bases has been well established.Coincidently,both reaction conditions for the synthesis of aryl sulfimines and its dehydrative rearrangement previously developed in our lab are similar to each other.Based on it,this paper aims to explore the one-pot dehydrative rearrangement reaction of aryl sulfoxides with amides and how to combine the aforementioned two reactions.After great efforts,we determined our hypothesized reaction could be realized using a simple Tf₂O/Et₃N system.The reaction has a broad applicable substrate scope,with a variety of functional groups including halogens,nitriles,cyano and carbonyl groups were well tolerated.In addition,the reaction is able to adopt benzenes,naphthalens and heteroaryl substrates.The reaction may proceed via two stages.First,aryl sulfoxides and amides,Under the presence of Tf₂O and Et₃N,one molecule of Tf OH is removed to give aryl N-acyl sulfimides,Subsequently,the same anhydride and base transform aryl sulfimines into aryl sulfimines to ketenimine sulfonium salts,which undergoes[3,3]-σrearrangement to give final product.This study developed the rearrangement of aryl sulfoxides with simple amides,thus a new protocol for advancing the sulfonium salt based rearrangement reactions.