Patent ID: 7816525

Claim:
A process for preparing tetrahydropterin of the following formula or a tetrahydropterin compound of said tetrahydropterin that is substituted at the 6-, or 7- or 6- and 7-position or positions, comprising hydrogenating pterin of the following formula or a pterin compound of said pterin that is monosubstituted at the 6-, or 7- or 6- and 7-position or positions, with hydrogen in a polar reaction medium in the presence of a hydrogenation catalyst that is a metal complex that is soluble in the reaction medium, wherein the catalyst contains a ligand which is (i) triarylphosphine, (ii) tetramethylene phenylphosphine (iii) pentamethylene phenylphosphine, or (iv) a bidentate ligand with a tertiary amine group and a phosphine group or with two tertiary phosphine groups as complexing groups, wherein the bidentate ligands form together with a metal atom a five- to ten membered ring.