59. A General One-Pot Synthesis of 2H-Indazoles Using an Organophosphorus-Silane System
J. Schoene, H. Bel Abed, P. Schmieder, M. Christmann, M. Nazaré
A simple and direct approach for the regioselective construction of the privileged 2H‐indazole scaffold is described. The developed one‐pot strategy employs a phospholene mediated N‐N bond formation to access 2H‐indazoles. The amount of organophosphorus reagent was minimized by recycling the phospholene oxide with organosilanes as reductant. Starting from functionalized 2‐nitrobenzaldehydes and primary amines a mild reductive cyclisation, using commercially available phospholene oxide and silanes, delivered a wide variety of substituted 2H‐indazoles in good to excellent yields.