Study On Rhodium(Ⅲ)-catalyzed C-H Activation In Tandem Construction Of Carbon-carbon And Carbon-nitrogen Bonds

Carbon-carbon and carbon-nitrogen bonds are the two most common bonds in organic chemistry.Heterocyclic compounds with carbon-nitrogen bond are widely distributed in various biologically active natural products and have historical significance in the development of pharmaceuticals and agrochemicals.In the past few decades,scientists have been seeking new methods for constructing carbon-carbon bonds and carbon-nitrogen bonds.The direct functionalization though transition-metalcatalyzed C-H activation has been favored by scientists due to its high efficiency and made great progress.However,most methods can only achieve mono-C-H functionalization and methods that can simultaneously construct carbon-carbon bonds and carbon-nitrogen bonds in tandem have been less developed.Arenes and alkenes are the simplest but indispensable chemical precursors which have multiple C-H activation sites and have been important substrates for studying CH difunctionalization.However,double C-H functionalization of arenes is often nonselective and/or uncontrollable and largely limited to introduction of the same or similar two coupling partners,let alone more complicated carboamination which can build carbon-nitrogen and carbon-nitrogen at the same time.By comparison,carboamination of alkenes developed more vigorous and can be divided into three kinds: radical-based reactions,intramolecular approaches,intermolecular approaches according to reaction mechanism and pathway.Intramolecular approaches have been thoroughly studied,and usualy a nitrogen-containing partner is tethered to the alkene.Carboamination of alkenes with a carbon-containing group connected to it via C-H activation have not been reported.In this context,we chosen alkene-tethered benzamides as starting materials and unactivated arenes as carbon source and 1,4,2-dioxazol-5-one derivatives as the amination reagents to explore the reactions and optimize the reaction conditions.We have founded three categories methods with tandam construction of carbon-carbon and carbon-nitrogen bonds in very similar reaction system though C-H activation: 1)Rh(Ⅲ)-catalyzed intramolecular olefin carboamination to synthesis N-((3-methyl-2,3-dihydrobenzofuran-3-yl)methyl)amides;2)Rh(Ⅲ)-catalyzed asymmetric C-H carboamination of arenes to synthesis furanoquinazolinone derivatives;3)Rh(Ⅲ)-catalyzed intramolecular olefin carboamination cascade aromatic C-H amidation/cyclization reaction to synthesis dihydrofuro-quinazolinone derivatives.All three type reactions have a wide range of substrates in good yield and can be selectively controlled only by the directing group and additives.