Processes for the preparation of pterin derivatives

Abstract From the Canadian patent

A process of preparing ~-biopterin is disclosed which comprises the steps of:, Subjecting to selective Grignard reaction D-ribose having the hydroxyl groups in the 2- and 3-positions protected by an acetal group to give , 6-deoxy-3,4-O-alkylidene allitol; subjecting the 1- and 2-positions of said allitol to oxidative cleavage to form 5-deoxy-2,3-O-alkylidene-L-ribose followed by deacetalization to give 5-deoxy-L-ribose; reacting 5-deoxy-L-ribose with a hydrazine compound to form a 5-deoxy-L-ribose hydrazone compound; and subjecting said hydrazone compound to condensation reaction with an acid addition salt of 4-hydroxy-2,5,6-triaminopyrimidine followed by oxidation.