Rh(?)-Catalyzed C-H Cyanation Of 2H-indazole

Indazoles have been recognized as an important class of N-heterocycles due to their prevalence in natural products,pharmaceutics,and bioactive compounds.And Aromatic nitriles are versatile in nature products with diverse applications in pharmaceuticals,dyes,agrochemicals,and materials.Owing to the above reasons,chelation-assisted strategy was utilized for the one-pot cyanation of 2H-indazoles.This reaction employed 2-aryl-2H-indazoles as substrate,NCTS as the cyano source,[Cp*Rh Cl2]2 as the catalyst,Ag Sb F6 as additive,Na OAc as base in 1,2-dichloroethane under air to access cyanated 2-aryl-2H-indazoles.Based on mechanistic studies and relevant literature,a plausible reaction mechanism was proposed.The main research contents are as follows:2-Phenyl-2H-indazole and NCTS were chosen as model substrate and the optimized conditions were confirmed through systematic investigations.With optimized conditions in hand,the substrate scope of 2-aryl-2H-indazoles was investigated.Various substituted 2H-indazoles were well tolerated to afford cyanated phenylindazoles in moderate yields with the highest result achieved in up to 94% yield.The nitrile group could undergo multiple transformations to other important functional groups,such as amines,amides and esters.To gain insight into the cyanation mechanism,H/D exchange experiment,the kinetic isotope effect(KIE)parallel and competitive experiments and intermolecular competition reaction were carried out for the proposal of mechanism.