S-epimer of 20-ethyl-9alpha, 11 alpha, 15-trihydroxy-5-cis-13-trans - prostadienic acid prodn from p-phenylbenzoate esters

摘要

One or both C15-epimers of formula (I): or its ester with a 1-6C alkanol is prepd. by crystallising a mixt. of epimers of the p-phenylbenzoate ester of formula (II): which contains >=50% of 1 epimer to give cpd. (II) enriched to >=75% with this epimer. The crystallisation solvent used is a mixt. of ethylacetate and pet. ether (60-80) at 1:3 to 1:5. The mother liquors are additionally chromatographed over a Kieselgel column eluted with ethylacetate/CH2Cl2=1:9. The combined fractions of high S-epimer (II) are then used in the synthesis of (I) which will contain >=75% of its S-epimer. The pure S-epimer is then obtd. by crystallisation. The inter. fraction contg. the other epimer can be oxidised to the ketone, reduced to the alcohol and used again. The S-epimer of (I) has luteolytic activity.