Synthesis and electrochemical behaviour of 2-N-substituted indazoles

Abstract

A new 2-N-aryl-3-methoxycarbonylindazole synthesis from the 6 F mol-1 reduction of appropriately substituted aryl-nitrones has been developed. The indazoles bearing an electron withdrawing group in the 2-position are electroreducible compounds at high negative potentials producing selectively the corresponding 2-N-substituted indazolines in aqueous alcoholic medium. The nitrile and ester groups are not reduced under the reaction conditions. Three new 2-N-arylindazolines were synthesized and characterized. A second electron withdrawing group attached at the 3-position leads to a less cathodic reduction of the 2-N-aryl-3-methoxycarbonylindazole. An appropriately substituted indazoline was used to generate in situ a new tetracyclic heterocycle.