Activatied Sulfoxide Mediated C-H Functionalization

The C-H functionalization reactions directly and efficiently install different functional groups onto the inert C-H bonds,and represent one of the hotspots in synthetic organic chemistry.Transition-metal-related C-H functionalization has been studied extensively,but transition-metal-free versions still remain underdeveloped.Activated sulfoxide intermediates have been widely used in organic synthesis due to their high activity and high electrophilicity.From early DMSO-DCC system for alcohol oxidation to sulfoxide-Tf2O system for C-H functionalization,activated sulfoxides have shown their wide applications.In this dissertation,we described the studies on activated sulfoxide-mediated C-H functionalizations.(1)Sulfoxide-Tf20 mediated allylic C-H alkylation reaction was developed.This method is applicable to tri-and disubstituted olefins,and even less reactive monosubstituted olefins are suitable for this reaction.This method is a novel transition-metal-free one-pot procedure.The sulfonium salt intermediate was isolated to verify the proposed mechanism.(2)The first activated sulfoxide mediated propargylic alkylation was realized.This method is suitable for simple symmetrical alkynes and silyl-substituted terminal alkynes.The current method is a novel transition-metal-free one-pot procedure.The allenyl sulfonium salt intermediate was isolated to verify the mechanism.(3)We discovered an unexpected pyridine-nitrogen-participated Pummerer reaction.The reaction was developed as a new way for synthesizing pyridin-2-one derivatives,which avoids the problemetic mixture products by O-or N-alkylation in the traditional method.