Oxidation of sulfamides and triazinones.

The Favorskii and Ramhurg-Backlund reactions are reviewed, together with the thermolysis and photolysis of ketones and sulfones. In contrast with N?'-dialkyl sulfamides the hypochlorite oxidation of diaryl sulfamides is not found to be a general route to aromatic azo compounds; instead the major products are usually quinoneanils, formed in a new aromatic rearrangement. Photolysis of the aryl sulfamides and thermolysis of their N?-dichloro derivatives do give azo compounds, however. The photochemical reaction appears to be intramolecular, possibly involving extrusion of sulfur dioxide as the first step. Part II. Oxidation of 3-aminobenzotriazin-4-ones with lead tetra-acetate proceeds by two independent routes, involving the loss of one mole of nitrogen to form indazolones and of two moles of nitrogen to form benzocyclopropenones. The indazolones, which can be intercepted by dienes, react with nucleophiles without rearrangement of the carbonyl group. Benzocyclopropenones react with nucleophiles with rearrangement of the carbonyl group to give isomeric pairs of benzoic acid derivatives. Concerted fragmentations of intermediate amino-nitrenes are proposed to explain these results. The mechanisms suggested are supported by a 15N-labelling experiment and by extended H?ckel molecular orbital calculations. A method is described for the gas phase thermal fragmentation of cyclic ?-carbonyl azo compounds. By this method 3-indazolone gave biphenylene and phthalaz-1,4-dione gave benzocyclobutene-1,2-dione