Synthesis of Oxygenated Derivatives

Reindel reported the synthesis of 7,7 -diazaindigo by oxidation of the sodium salt of 7-azaindoxyl, for which he ascribed structure 86 or 87, and it was prepared in near quantitative yield by heating iV-(2-pyridyl)aminoacetic acid with 30% sodium hydroxide. The 

94 According to Chemical Abstracts 3-Hydroxy-lfl -pyrrolo[2,3-b]pyridine-2-carboxylic acid. The common names indoxyl, oxindole, and isatin will be used as they do not imply which tautomer is predominant. It is noted that the tautomers shown are in accord with current theory for indoles and have not been established as such. 

In 1953, Cookson reported the cyclization of porphobilinogen (92, R = H) to give the pyrrole lactam (93, R = H), a derivative of 4,5,6,7-tetrahydro-6-azaindol-5-one. Jackson et a(. synthesized the diacid (93, R = CO2H) from the triacid (92, R = CO2H) by a difier-ent route, then decarboxylated it to the lactam (93, R = H) in 80 % 

Okuda and Robison prepared 7-azaoxindole (90, R = H) in 67% yield by heating 2-aminop3uridine-3-acetic acid at 225° under nitrogen. Their attempts to synthesize 5-azaoxindole from 3-bromo-4-acetamidop5Tidine by creation of an intermediate pyridyne species were unsuccessful. Ficken and KendalR obtained a small amount of 3,3-dimethyl-7-azaoxindole (90, R = Me) by heating l-isobutyryl-2-(2-pyridyl)hydrazine with calcium oxide. They were 

To date, none of the above syntheses appears to be a suitable route to nonoxygenated azaindole derivatives. 

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Singh, S.K. and S. Kumar. 1993. Synthesis of oxygenated derivatives of 2,3,7,8-tetra-chlorodibenzo-p-dioxin.. Agric. Food Chem. 41 1511-1516. 

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