Palladium Catalyzed C-H Arylation Of Aryl Sulfonamides And Copper Catalyed C-N Bond Cleavage

In this thesis,we mainly investigated the palladium catalyzed C-H bond arylation of aryl sulfonyl aminoacids;a novel method for the synthesis of biaryl sulfonamide derivatives has been developed.The related reaction mechanism was explored.At the same time,we realize copper catalyzed C-N bond cleavage of aryl sulfonamidate acid,providing a new way to synthsis primary aryl sulfonamides.This thesis consistes of two parts:(1)Palladium-catalyzed ortho C-H arylation of aryl sulfonamidesAn efficient method for the synthesis of biaryl sulfonamide derivatives by using aryl sulfonamides and aryl iodides as substrates has been developed via palladium(II)-catalyzed C-H bond activation.The protocol proceeded efficiently in water;high yields were achieved.The reaction shows good functional group compatibility and proceeds in a highly selective manner at the ortho position of arenes connected to sulfonamide sulfur atoms.Mechanistic studies show that the present bidentate directing group is essential for promoting ortho C-H bond activation of arenes connected to sulfonamide sulfur atoms,and the palladation process is reversible and not involved in the turnover-limiting step.Finally,a plausible reaction mechanism is proposed.(2)Copper-catalyzed C-N bond cleavage of aryl sulfonamino acidsInitially,we realized copper catalyzed C-N bond cleavage of sulfonamino acid in present of copper oxide as catalyst,in DMSO at 100℃ for 8h.The present protocol provides an efficient method for the synthesis of primary aryl sulfonamides in excellent yields.Then,we have developed a straightforward route to the synthesis of primary biaryl sulfonamides via palladium(II)/copper(I)-catalyzed sequential C-H arylation and oxidative C-N bond cleavage of aryl sulfonamino acids.In present protocol,the first step for C-H bond arylation reaction was conducted well in present for Pd(OAc)2 and NaOAc,in CH3 CN at 100℃ for 12 h.The amino acid moiety could be sequentially removed in one-pot reaction by adding CuI as the catalyst and air as a sole oxidant for further 8h.The mechanic study was explored,and a plausible reaction mechanism is proposed.Initially,the Cu-catalyzed oxidative decarbonylation reactions generate the corresponding iminium intermediate.Secondly,the imine intermediate is delivered after deprotonation.Finally,the imine is hydrolyzed to afford the primary aryl sulfonamide and aldehyde.