The Chemistry of Indoxazenes and Anthranils: 1966–1979

This chapter discusses the physical, chemical, and spectroscopic properties of indoxazenes and anthranils. Indoxazenes can be prepared from o-halogenobenzoyl compound, o-nitrophenylacetic acid and its derivatives, and o-hydroxybenzoyl oximes and its related compounds. The miscellaneous method employed for the preparation of indoxazenes includes cycloadditions involving nitrile oxides associated with the production of reduced indoxazenes. Ring transformations of indoxazenes are effected under acidic, basic, thermal, and photolytic conditions. The reduced derivatives of indoxazenes are dihydroindoxazenes, tetrahydroindoxazenes, hexahydroindoxazenes, and octahydroindoxazenes. Anthranils can be prepared from o-nitro and o-nitroso compounds, o-amino compounds, by reaction of benzyl cyanides with nitroarenes, and from o-azidocarbonyl compounds. Oxidation of 3-arylanthranils is a useful preparative route to o-nitrobenzophenones. The reduction of anthranils is a particularly valuable route to 5-chloro-2-aminobenzophenones, the precursors of benzodiazepinones of the valium and librium type. A novel one-step synthesis of tricycloquinazolines is described involving treating anthranils with ammonium acetate in a mixture of acetic acid and sulfolane.