Transition Metal Rhodium Catalyzed [3+2] Cycloaddition Reaction

The construction of carbon-carbon bonds and carbon heterobonds is an important research area in organic synthesis chemistry.Among them,transition metal-catalyzed C-H bond activation attracts much attention due to its good atomic economy,environmentally friendly carbon-carbon bond formation and carbon hetero-bond reaction.At present,the activation of C-H bonds catalyzed by heteroatom-oriented groups of transition metals(Pd,Rh,Ru,Fe,Co,Cu,Ni,etc.)has developed rapidly and has become one of the commonly used methods for constructing C-C bonds.In this these,we first reviewed the synthesis of cyclized compounds by rhodium-catalyzed C-H bond activation,including the cyclization of oxygen-containing groups,nitrogen-containing groups and amide functional groups with olefins and alkynes.Inspired by these efforts,this paper mainly did the following work:(1)The oxidative cyclization of phosphonium-catalyzed imine substrates with electron-deficient olefins was studied.First,the use of the substrate was determined,and the two catalytic systems were optimized for screening to obtain the best reaction conditions.After that,the use range of the substrate for the reaction system was performed.The cyclic imine-imine substrate with electron donation can produce a five-membered carbocyclic ring structure with a chiral amine,while the cyclic imine of an electron-withdrawing group requires more severe reaction conditions.The unprotected aldehydes and ketones can also efficiently construct this structure.Similarly,the aldehyde and ketone imine reaction requires twice as much catalyst and ten times as much copper acetate as the cyclic imine.However,the same reaction has high catalytic efficiency,a wide range of practical use of the substrate,and good compatibility with many functional groups.(2)The rhodium-catalyzed cyclization of cyclic imines with alkynes was studied.This ringing reaction is different from the addition of cyclic imine and olefin.Under the optimal conditions,the reaction of the alkyne needs to change the catalytic solvent THF to DMF,other conditions remain unchanged,but the same higher efficiency is obtained.The corresponding five-membered carbon ring structure.However,the group attached to the benzene ring on the cyclic imine has little effect on the reaction.The electron-poor alkynes react better.