Preparation method of 5,6,7,8-tetrahydro-imidazo[1,5-a]pyrazine-1-carboxylic acid ethyl ester

The present invention relates to a 5,6,7,8-tetrahydro - imidazo [1,5-a] pyrazine -1-carboxylic acid ethyl ester derivatives, mainly solve the conventional synthetic methods do not yield high purification is difficult, inconvenient operation experimental technical problem, the present invention comprises the following steps (1): preparation of 2-methylthio-pyrazine; (2): oxidizing the methylthio group; (3): methyl sulfone group ring closure; (4): pyrazine hydride reduction. The following reaction formula:, the present invention is obtained 5,6,7,8-tetrahydro - imidazo [1,5-a] pyrazine-1-carboxylate - derivative is useful intermediates for the synthesis of many drugs or product.