Synthesis of 1,2,3,4-tetrahydropyrido- [2,3-<Emphasis Type="Italic">b</Emphasis>]pyrazine-2,3-dione derivatives with a chiral substituent at the nitrogen atom

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-tetrahydropyrido2,3-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 imidazo4,5-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. Dedicated to Academician J. Stradins in connection with his 75th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 237-243, February, 2009.