Regioselective Synthesis of 2H-Indazoles Using a Mild, One-Pot Condensation–Cadogan Reductive Cyclization
摘要:
An operationally simple and efficient one-pot synthesis of 2H-indazoles from commercially available reagents is reported. Ortho-imino-nitrobenzene substrates, generated via condensation, undergo reductive cyclization promoted by tri-n-butylphosophine to afford substituted 2H-indazoles under mild reaction conditions. A variety of electronically diverse ortho-nitrobenzaldehydes and anilines were examined. To further extend the scope of the transformation, aliphatic amines were also employed to form N2-alkyl indazoles selectively under the optimized reaction conditions.
Ionic diamine rhodium complex catalyzed reductive N-heterocyclization of N-(2-nitroarylidene)amines
作者:Kazumi Okuro、Joanna Gurnham、Howard Alper
DOI:10.1016/j.tetlet.2011.11.101
日期:2012.2
Ionic diamine rhodiumcomplexescatalyze the reductive N-heterocyclization of N-(2-nitroarylidene)amines under carbon monoxide to afford the corresponding 2H-indazoles in up to 75% yields.