Preparation process of (6R)-tetrahydro-L-biopterin

摘要

(6R)-Tetrahydro-L-biopterin of the following formula: <IMAGE> is prepared by catalytically reducing L-erythrobiopterin or an acyl derivative thereof in the presence of an amine, at pH 10-13 and with a platinum-base catalyst and when one or more acyl groups still remain, then removing the acyl groups. (6R)-Tetrahydro-L-biopterin is effective for the treatment of certain serious neuroses and malignant hyperphenylalaniemia. The present invention has succeeded in preparing (6R)-tetrahydro-L-biopterin at a high asymmetric ration R/S and moreover with a high yield. Since the process of this invention makes use of an amine as a base, the process is free from admixture of any inorganic salt and can hence provide high-purity crystals with ease.