Synthesis of 1,2,3,4-tetrahydropyrido- [2,3-b]pyrazine-2,3-dione derivatives with a chiral substituent at the nitrogen atom
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The sequence of steps including nucleophilic substitution of the chlorine atom in 2-chloro-3-nitropyridine by esters of optically active phenylalanine, reduction of the nitro group, acylation with ethyl oxalyl chloride, and intramolecular cyclization, leads to the synthesis of derivatives of 1,2,3,4-tetrahydropyrido[2,3-b]pyrazine-2,3-dione with a chiral substituent at the nitrogen atom. It was established that, depending on the conditions of carrying out the cyclization, the parallel formation of derivatives of imidazo[4,5-b]pyridine is possible. Conditions were found for selectively carrying out the cyclization under with only structures of pyrazines or imidazole condensed with pyridine were formed.
Keywordstert-butyl ester of imidazo-[4,5-b]pyridine-2-carboxylic acid 2-chloro-3-nitropyridine, 1,2,3,4-tetrahydropyrido[2,3-b]pyrazine-2,3-diones chiral substituent at the nitrogen atom esters of optically active phenylalanine nucleophilic substitution
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