Über Pterinchemie 80. Mitteilung Die Herstellung von (6 RS )Tetra‐ und (6 RS )Pentaacetyl‐5,6,7,8‐tetrahydro‐L‐bioplerinen

Preparation of (6 RS )Tetra‐ and (6 RS )‐Pentaacetyl‐5,6,7,8‐tetrahydro‐L‐biopterines Boiling of (6 RS ) l′‐ O ,2′‐ O ,2‐N‐triacetyl‐5,6,7,8‐tetrahydro‐L‐biopterine in acetic anhydride as described in [2], leads to a mixture of the diastereoisomeric (6 R )‐ and (65)‐l′‐ O ,2′‐ O ,2‐ N ‐,5,8‐pentaacetyl‐5,6,7,8‐L,‐biopterines. One of the diastereoisomers can be obtained as pure crystals. It corresponds to the pentaacetate of the natural (6 R )‐ or (6 S ).,5,6,7,8‐tetrahydro‐L‐biopterine. For the preparation of the earlier described (6 RS )‐ and (6 S )‐tetraacetyl‐tetrahydro‐L‐biopterines [2] improved conditions are reported.