Transition Metal-catalyzed Cross-dehydrocoupling Reactions Involving Olefins

Cross-Dehydrogenative coupling reaction,as a burgeoning synthetic methodology,has been widely used in organic synthesis,such as the construction of C-C,C-N,C-O bonds.This paper focus on the formation of C-C,C-N bonds,and includes two parts.(1)Palladium catalyzed Aza-Wacker-Type reaction between electron-deficient olefins and N-alkylsulfonamides.Sulfonamide is a kind of important substrate,which is widely exist in drugs and dyes.Besides,sulfonyl is also a good protecting group to amino.The oxidative sulfonamidation of electron deficient olefins has been achieved for the first time.After screening the reaction conditions,the best reaction condition was confirmed:using palladium acetate as the catalyst,SelectfluorTM as the oxidant and methane sulfonic acid as the additive.This paper also explored the scope of the substrates with a variety of substituted sulfamides and electron deficient olefins.A wide range of substituted sulfamides can get good yield.A series of electron deficient olefins could coupled with the substrate.Acrylates gave good yield.(Vinylsulfonyl)benzene and dimethyl vinyphosphonate were able to form the corresponding product in moderate yields.The mechanism study revealed that the reaction undergoes a Pd(II)/Pd(0)catalytic cycle.In addition,the palladium methanesulfonate may be the real catalyst.(2)Rhodium catalyzed regioselective synthesis of 8-substituted indolizine via C-H activationIndolizine is an important substrate,which contains 10π electrons and is widely used in drugs and fluorescent materials.We tried to activate the C-H bond of indolizine,and coupled with the electron-deficient olefins.After screening the reaction conditions,the best reaction condition was confirmed:using[RhCp*Cl2]2 as the catalyst,copper acetate as the oxidant and trifluoroethanol as the solvent.This paper also explored the scope of electron-deficient olefins.A wide range of olefins can get moderate to good yields.