Patent ID: 6177579
Filing Date: 2001-01-23
Classification: A61P,C07B,C07C

Abstract:
A process for the preparation of 13-cis-retinoic acid (I) ##STR5##free from heavy metals traces, comprising the following steps:a) reacting beta-ionone (IV) with a vinyl magnesium halide (V): ##STR6##(X--Cl, Br, I)to give vinyl-beta-ionol (VI);b) carrying out a Wittig condensation of vinyl-beta-ionol (VI) with 4-hydroxy-3-methyl-butenolide (VII) according to conventional methods to give a mixture of 13-cis-retinoic acid (I), 11-13-di-cis-retinoic acid (II) and 11,13 di-trans-retinoic acid (III): ##STR7##c) carrying out a photochemical isomerization, in an aqueous solution, of the alkali metal salts of the acids from step b).