Rh(Ⅲ)-Catalyzed Multicomponent Reaction Cascade Involving Multiple C-H Activation

With the development of modern organic synthetic chemistry,people are not only pursuing the construction of complex molecules but also pursuing the greenness and efficiency of synthesis.In this background,starting directly from a simple and easily available substrate,the transition metal-catalyzed C-H functionalization reaction has shown good atom and step-economy in the construction of Carbon-carbon and carbon-heteroatom bonds,which is a synthetic strategy in line with the concept of sustainable development.In order to further improve the synthesis efficiency,the development of highly efficient cascade reactions involving the cleavage and reformation of multiple chemical bonds have a unique advantage over traditional step-by-step synthesis methods in the rapid construction of molecular complexity.In recent years,people have achieved fruitful results in the research and application of cascade reactions,which have become one of the most active research areas in modern organic synthesis.On this trend,the multi-components reaction cascade initiated by C-H bond activation possessing high atom and step-economy,combined with the high efficiency of Rh(Ⅲ)catalysts in the synthesis of heterocycles and excellent functional group tolerance.The strategy is expected to provide new ideas in the post-modification and rapid construction of bio-molecule and functional material.In this paper,we have mainly studied the multi-components reaction cascade involving multiple C-H activations catalyzed by Rh(Ⅲ).The main contents of this paper include: 1.Introduction: The history and current status of studies on Rh(Ⅲ)-catalyzed imine-structure directed reactions cascade reactions The origin,development and current status of Rh(Ⅲ)catalyst and its imine-structure directed system are briefly introduced,and research results in this field are briefly reviewed.2.Sequential C-H and C-C bond cleavage: divergent constructions of fused N?heterocycles via tunable cascade We have achieved imidate-directed multiple cascade reactions for the divergent assembly of fused N-heterocycles,comprising sequential activation of C-H and C-C bonds.Isolatable indene-type intermediates,the tolerance of various functional groups and strongly coordinating groups,via tunable reaction conditions,the divergent synthsis of three different fused pyridines,azepines,and azafluorenones products.3.Sequential assembly of densely substituted isoindolines via aerobic oxidative multicomponent reaction cascade We have achieved a simple and readily available aldehyde or amine as the reaction substrate to generate Schiff base compunds in situ.Under the catalytic action of Rh(Ⅲ),a cascade reaction initiated by C-H activation has achieved rapid construction of polysubstituted isoindolin compounds.4.Programmed oxidative C-H/C-H couplings of arenes with olefins: controllable synthesis of aromatic nitriles The direct oxidation C-H/C-H coupling strategy holds great synthetic advantages and challenges for the rapid constructions of molecular libraries.By tuning the additives,we have achieved a controllabe coupling reaction of aromatics and olefins to generate various arylimidates or arylnitrile.