Lewis Acids Catalyzed Regiodivergent N-alkylation of Indazoles with Donor-Acceptor Cyclopropanes

N-alkyl Indazoles are highly privileged skeleton in pharmaceutical applications. Generally, N1 and N2-alkyl indazoles represents distinct pharmaceutical and biological activities due to their molecular shape and electrostatic distribution. Herein, we described a regiodivergent N-alkylation of indazoles via nucleophilic ring opening of D-A cyclopropanes by employing different Lewis acid catalysts. Under the catalysis of Al(OTf)3, kinetic controlled N2-alkyl indazoles were achieved, while Co(NTf2)2 facilitated the formation of N1-alkyl indazoles. The methodology exhibited a broad substrate scope, affording the corresponding N1 and N2 alkylation products selectively in high yields with good to excellent regioselectivities.