The Chemistry of the Benz[cd]indazole System. Benz[cd]qindazole 1-Oxide, Benz[cd]indazole 1,2-Dioxide (1,8-Dinitrosonaphthalene), and Related Compounds

Abstract

Two routes to benz[cd]indazole 1-oxide (V) and benz[cd]indazole 1,2-dioxide (IV), and the preparation of 1-nitro-8-nitrosonaphthalene (VI), are described, and the potential valence tautomerism of these compounds is discussed. Benz[cd]indazole 1,2-dioxide is converted by alkali metal alkoxides into 3- and 5-alkoxybenz[cd]indazole 1-oxides (XII) and (XIII). Reduction of the 1-oxide bypasses benz[cd]indazole itself and gives 1,3- and 1,5-dihydrobenz[cd]indazoles (VII) and (VIII) and 1,3,4,5-tetrahydrobenz[cd]indazole; oxidation of the dihydrobenzindazoles, and other potential synthetic processes, fail to give benz[cd]indazole. Possible reasons for expecting this compound to be unusually reactive are considered.