Pyrolysis azido compounds

Several attempts to make this compound by pyrolysis of 2-azidO-3-nitro-naphthalene failed (ref. 35). 

Attempts to prepare 6-hydroxybenzofuroxan by demethylation of 5-methoxybenzofuroxan, by pyrolysis of 4-azido-3-nitrophenol, and by hypochlorite oxidation of 4-amino-3-nitrophenoD failed. This rather unstable compound was finally prepared by hydrolysis of 5-acetoxybenzofuroxan its tautomeric possibilities are numerous, but from the similarity of its ultraviolet spectrum to that of 5-methoxybenzofuroxan it was considered to be largely in the hydroxy form. It is a fairly strong acid, of pK 6.76 (cf. 5-hydroxybenzo-furazan, pK 7.28). 7-Hydroxy-4,6-dinitrobenzofuroxan has been reported as arising from oxidation and nitration of dinitrosoresorcinol monooxime (tetraoxocyclohexene trioxime). ... 

N-Oxides 230 and 231 are stable benzo[o/]indazole derivatives. A mixture of these compounds was obtained on pyrolysis of l-azido-8-nitronaphthalene 228 or on oxidation of 1,8-naphthalenediamine 229. It... 

The pyrolysis of 3-azido-4-dialkylaminopyridines (424) and (427) by heating in nitrobenzene to generate nitrene intermediates (425) has also been used to form the imidazole ring of imidazo[4,5-c]pyridines (426) and (428) (66JCS(C)80). In one instance the intermediate dihydro compound (429) was trapped by carrying out the reaction in acetic anhydride (63JCS1666). 

Pyrrolo[l,2-a]indolequinones were prepared also by cyclization reactions. One of them involves copper-catalyzed pyrolysis of 2-azido-5-methoxy-6-methyl-3-(2,4-pentadienyl)-l,4-benzoquinone to give compound 45 (87JOC3956). The second pyrrole ring was also formed from a 2-hydroxy-propyl side chain of an indolo-4,7-dione (80JOC5057). Benzo analogs were prepared in a Friedel-Crafts reaction from either phthalic anhydride (67TL765) or 2-pyrrolidinylcarbonyl chloride (86H2797). 

One of the most ubiquitous reactions is the formation of azo compounds by the attack of nitrene on the azido group. This process accounts for the high overall quantum yield of nitrogen evolution in the gas phase photolysis of hydrazoic acid and of methyl azide It has also been demonstrated in the gas phase pyrolysis of phenyl azide and of or//jo-trifiuoromethyl azide where azobenzenes arc the major reaction products. Azo compounds are formed in near quantitative yield in the solution photolysis of / -methoxyphenyl azide and... 

Thermolysis of terminal vinyl azides has generally led to the isolation of products other than azirines. A number of j8-azido-styrene derivatives have, on pyrolysis, yielded indoles. Thus /S-azido-a-methylstyrene, (60) when boiled in mesitylene, produced an 80% yield of 3-methylindole (61) and 9% of a-phenylpropionitrile (62) Decomposition of the same compound in ethanol, however, gave only a trace of the indole the major product, isolated in about... 

Pyrolysis of the compounds 250 yields nitrene intermediates, which undergo a wide range of insertion reactions.502 529 W-Cyanopyrroles, which are obtained from the pyrolysis of tetrazolopyridines, also arise from nitrene intermediates via ring contraction.512,530 Mass spectral studies have indicated that the first step in the gas-phase pyrolysis of fused tetrazolopyridines and pyrimidines involves tautomerism to the azide with subsequent nitrene formation.523 Copper compounds have been found to catalyze the generation of nitrene intermediates from the compounds 250 and 244.531 The compounds 250 also undergo cycloaddition reactions through the azido form.511... 

Cyano derivatives of (18) are prepared by reaction of o-phenylenediamine with o-CcH4(CO)2N(CH2) COC(CN)=NC6H4NMe2-p. Hydrolysis of the latter compounds give intennediates of the type o-C H4(CO)2N(CH2) COCOCN which on condensation with o-phenylenediamine yield 3-phthalimidoalkylquinoxalin-2-ones. 6,7-Disubstituted quinoxalines have been prepared from 2,4-diazido-1,5-dinitrobenzene (19), which on pyrolysis is converted into 2-azido-... 

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