Roussel Uclaf

Jacques Marechal-Prost

Julien Warnant

Philippe Cosquer

A process for the preparation of an ester of chiral (A) acid with an optically active (S) .alpha.-cyano-3-phenoxybenzyl alcohol by reacting an ester of chiral (A) acid with .alpha.-cyano-3-phenoxybenzyl alcohol of the formula ##STR1## in its optically active (R) form or a racemic (R,S) mixture or a mixture of esters of said (R) alcohol and (S) alcohol in non-equimolecular proportions designated herein as 'ester (R+S)' with a base selected from the group consisting of ammonium hydroxide, primary, secondary and tertiary amines, quaternary ammonium compounds, liquid amines of high molecular weight, ion exchange resins of a basic character and a catalytic amount of a strong base in at least one solvent in which the ester of the (R) alcohol is soluble and in which the ester of the (S) alcohol is insoluble and recovering from the resulting medium the chiral (A) acid ester of the (S) alcohol which is insoluble.

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Paris, France

Jacques Marechal-Prost