Rhodium Catalyzed Non-aromatic C(sp~2)-S Construction Via C-H Activation

C-H bond activation has attracted much attention because of its high regioselectivity and atom economy.Transition metals are considered as ideal C-H bond activation catalysts due to their wide range of oxidation states.Among them,rhodium and other precious metals have unique catalytic activities what enable them to participate in many reactions that are difficult to be catalyzed by inexpensive metals.Sulfur containing compounds are widely existed in organic building blocks,natural products and biopharmaceutical molecules.At the same time,they show superior properties in the field of materials.Therefore,the synthesis of sulfur containing compounds has always been the topic of organic chemistry.In recent years,C-S bond construction via C-H bond activation has been developed.But most of them are devoted to the research of aromatic compounds.In this paper,a series of non aromatic C(sp2)-S bond construction has been achieved through the direct activation of olefins.The work of this thesis is divided into the following two parts:In the first part,the construction of C-S bond directed by N-tosylacrylamide and catalyzed by[Cp*RhCl2]2 was studied.This strategy has high catalytic efficiency.The catalyst loading could be as low as 0.01 mol%,which led to a high TON(turnover number)of 7100.The system also showed good tolerance in substrate scope.A series of(Z)-?-alkenyl sulfides with potential biological activity could be obtained in moderate to excellent yield,respectively.In the second part,the first example of non aromatic C(sp2)-S bond construction catalyzed by simple inorganic rhodium salt and directed by easily derivable carboxyl group was developed.Electron-rich phosphine ligand played an important role in this transformation,which could apparently improve the yield.The reaction could be successfully enlarged to gram scale,and the product could be conveniently converted into thioflavone with physiological activity.It is worth mentioning that in this catalytic system,RhCl3·3H2O displayed higher catalytic activity than[Cp*RhC12]2,which made a tentative step in the field of simple inorganic rhodium salt catalyzed C-H bond activation.