Synthesis and electrochemical behaviour of 2-N-substituted indazoles

A new 2-N-aryl-3-methoxycarbonylindazole synthesis from the 6 F mol(-1) red uction of appropriately substituted aryl-nitrones has been developed. The i ndazoles bearing an electron withdrawing group in the 2-position are electr oreducible 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. Thr ee new 2-N-aryl-indazolines were synthesized and characterized. A second el ectron withdrawing group attached at the 3-position leads to a less cathodi c reduction of the 2-N-aryl-3-methoxycarbonylindazole. An appropriately sub stituted indazoline was used to generate ill situ a new tetracyclic heteroc ycle.