PROCESS FOR PREPARING (6R,7S,8R)-6,9-DIHYDROXY-7,8-ISOPROPYLIDENEDIOXY-2,4-NONADIENIC-ACID ALKYL ESTERS, AND USE THEREOF IN THE MANUFACTURE OF D-BIOTIN

摘要

Alkyl (6R,7S,8R)-6,9-dihydroxy-7,8-isopropylidenedioxy-2,4-nonadienoates of the formula I IMAGE (I) where R is alkyl of 1 to 4 carbon atoms are prepared by reacting 3,5-O-isopropylidene-D-arabinose of the formula II IMAGE (II) with a 3-carboalkoxyprop-2-en-1-ylidene triphenylphosphorane of the formula III IMAGE (III) in a solvent at elevated temperatures, by a process wherein the reaction is carried out in, as the solvent, a suitable aliphatic or aromatic hydrocarbon, a halogen derivative thereof or a cycloaliphatic ether, preferably an aromatic hydrocarbon of 6 to 8 carbon atoms, at from 65 to 130 DEG C., preferably from 80 to 115 DEG C. Using this process, the basic skeleton of d-biotin can be synthesized from D-arabinose in substantially better yields than obtainable hitherto.