Studies on the reaction of π-deficient heterocycles with aromatic aldehydes in the presence of cyanide ion was written by Higashino, Takeo;Goi, Masami;Hayashi, Eisaku. And the article was included in Chemical & Pharmaceutical Bulletin in 1976.Quality Control of Pyrido[2,3-b]pyrazine This article mentions the following:
Dimerization of π-deficient heterocycles was catalyzed by cyanide ion in Me2SO. Thus, reaction of quinoxaline, 1-phenyl-1H-pyrazolo[3,4-d]pyrimidine(I), 1-methyl-1H-pyrazolo[3,4-d]pyrimidine (II), and pyrido[2,3-b]pyrazine (III) with cyanide ion gave 2,2′-biquinoxaline, 4,4′-bis[1-phenyl-1H-pyrazolo[3,4-d]pyrimidine] (IV), 4,4′-bis[1-methyl-1H-pyrazolo[3,4-d]pyrimidine], and 2,2′-bispyrido[2,3-b]pyrazine, resp., although the yields of these dimers were very poor. π-Deficient heterocycles with RC6H4CHO (V, R = o-, m-, p-MeO, Cl, Me, etc.) in the presence of cyanide ion in Me2SO underwent a cross benzoin condensation reaction. Thus, 4-isoquinolinecarbonitrile reacted with V to give α-aryl-4-cyano-1-isoquinolinemethanol and aryl 4-cyano-1-isoquinolyl ketone together with 1,1′-biisoquinoline-4,4′-dicarbonitrile. Similarly, quinoxaline and V gave α-aryl-2-quinoxalinemethanol and aryl 2-quinoxalinyl ketone, I and V gave α-aryl-1-phenyl-1H-pyrazolo[3,4-d]pyrimidine-4-methanol and aryl 1-phenyl-1H-pyrazolo[3,4-d]pyrimidin-4-yl ketone, II and V produced α-aryl-1-methyl-1H-pyrazolo[3,4-d]pyrimidine-4-methanol and aryl 1-methyl-1H-pyrazolo[3,4-d]pyrimidin-4-yl ketone, and III and V formed aryl 2-pyrido[2,3-b]pyrazinyl ketone VI. In the experiment, the researchers used many compounds, for example, Pyrido[2,3-b]pyrazine (cas: 322-46-3Quality Control of Pyrido[2,3-b]pyrazine).
Pyrido[2,3-b]pyrazine (cas: 322-46-3) belongs to pyrazine derivatives. Pyrazines are volatile compounds that are used in the cosmetic, food, flavor, and fragrance industries. A number of pyrazine-based derivatives were used as dyes or fluorescent probes.Quality Control of Pyrido[2,3-b]pyrazine