Synthesis of 3C-alkylated active methylene substituted 2H-indazole derivatives via sequential ring opening of donor-acceptor cyclopropanes and reductive cyclization reaction

A concise sequential protocol is developed to synthesize 3C-alkylated active methylene substituted 2H-indazole derivatives via a nucleophilic ring opening reaction (NRO) of o-nitro donor-acceptor cyclopropanes (DACs) with primary arylamines catalyzed by Ni(ClO4)(2)center dot 6H(2)O followed by a SnCl2 center dot 2H(2)O-mediated intramolecular reductive cyclisation. The di-ester functionality can be transformed into the corresponding monoesters, acids, alcohols and amides that form the core units of important biologically active molecules.