Process for the separation of (S,S) diastereoisomers
AssigneeUSV Pharmaceutical Corporation
InventorsLaurence W. Reilly, Jr., Jeffrey N. Barton
Life of this patent
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Abstract
The (S,S) optical isomer of a compound having the general formula ##STR1## wherein R and R.sub.1-5 are as defined herein, is recovered essentially free of the (R,S) and (S,R) isomers, by forming a solution of the esters of the (S,S) and the (R,S) and/or (S,R) isomers of said compound, selectively precipitating an acid salt (e.g. maleate) of the (S,S) ester from the solution, and treating the precipitate to form the desired free acid.
Claims4
A process for separating the (S,S) diastereoisomer of a compound of the formula ##STR7## from a solution containing said (S,S) isomer and one or both of the corresponding (R,S) and (S,R) diastereoisomers in a non-polar, water-immiscible organic solvent selected from the group consisting of toluene, methylene chloride, diethyl ether, chloroform, ethyl acetate, and mixtures thereof, wherein R.sub.6 is t-butyl or benzyl, comprising
- (i) reacting said diastereoisomers with an acid, selected from the group consisting of maleic, tartaric, p-nitrocinnamic, cinnamic, hippuric, citric, and 2,4-dichlorobenzoic acids, which forms acid addition salts with said diastereoisomers which salts are characterized in that the salts of the (R,S) and (S,R) diastereoisomers are soluble in said solution and said salt of the (S,S) diastereoisomer is not, under conditions wherein the salt of the (S,S) diastereoisomer selectively precipitates from said solution, and
- (ii) converting said precipitated salt to the (S,S) compound of formula (A).
Dependencies are inferred from the claim text.