(A) study on the synthesis of pyrazine derivatives

Abstract

An improved synthetic method was investigated for 5-imino-7-oxo-2,3-disubstituted-5H-6,7-dihydropyrrolo[3,4-b] pyrazine. 2,3-Dicyano-5,6-disubstitutedpyrazines were prepared by the condensation of $\alpha,\beta$-diketones with diaminomaleonitrile following the method of F.D. Popp. In this study, two different synthetic methods were investigated for 5-imino7-oxo-2,3-disubstituted-5H-6,7-dihydropyrrolo[3,4-b]pyrazines. First, these compounds were prepared by reacting 2,3-dicyano-5,6-disubstituted-pyrazines with sodium methoxide following the method of Kojima and Ohtsuka. Secondly, these compounds were prepared by reacting 2,3-dicyano-5,6-disubstitutedpyrazine with hydrogen peroxide in the presence of weak base. In order to synthesize the compound which contain three carbonyl groups within its molecule, we reacted 5-imino-7-oxo-2,3-disubstituted-5H-6,7-dihydropyrrolo[3,4-b] pyrazine with oxalyl chloride in the presence of strong base.