Pyrrolo pyridine-6-carboxylates 7-hydroxy

Methoxycarbonyl methyl-1 //-pyrrolo 3,4-r pyridine-l,3(2//)-dione (47) has been reported to undergo ring expansion to afford methyl 4-hydroxy-1-oxo-l,2-dihydro-2,7-naphthyridine-3-carboxylate (48) (MeONa/MeOH, 100°C ... 

For the corresponding l//-2-hydroxypyrrolo[2,3-c]pyridine isomer, a mixture of both lactam and lactim forms has been observed in solution as well as in the crystalline state. It is interesting to note that the lactam tautomer predominates for l//-2-hydroxy-3-ethoxycarbonylpyrrolo[2,3-c]pyridine, whereas the lactim form is the major tautomer for the corresponding pyrrolo[3,2-6]pyridine derivative <74JCS(P1)1531>. Similarly, for 1 //-6-hydroxypyrrolo[2,3-6]pyridine, both lactam and lactim tautomers are present in solution and the crystalline states <66T3233>. For the 2-hydroxy derivative of compound (3), both IR and H NMR spectroscopy indicate that approximately equal amounts of the alcohol and carboxyl derivative are present <77CHE1224). 

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. 

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