Claims
- 1. A process for producing a desired substantially pure, R,R, isomer of a compound of formula I ##STR41## wherein R.sub.1 and R.sub.4 may be one or more groups which may be the same or different and are selected from the group consisting of hydrogen, C.sub.1 to C.sub.4 alkyl, C.sub.1 to C.sub.4 alkoxy, hydroxy, halogen, trifluoromethyl, carboxy, hydroxyalkyl, alkoxycarbonyl, C.sub.1 to C.sub.4 thioalkyl, sulfonyl and sulfinyl; X is a divalent radical consisting of ##STR42## wherein R' is hydrogen, R.sub.2 and R.sub.3 may be the same or different and are selected from the group consisting of hydrogen and C.sub.1 to C.sub.4 alkyl; R.sub.5 and R.sub.6 are selected from the group consisting of hydrogen, carboxy, alkoxycarbonyl, hydroxymethyl, --CH.sub.2 OCH.sub.2 COOR.sub.7 and --CH.sub.2 OCH.sub.2 CH.sub.2 OR.sub.7 where R.sub.7 is hydrogen or C.sub.1 to .sub.4 alkyl; except that R.sub.5 and R.sub.6 may not both be hydrogen; and the asterisks denote asymmetric carbon atoms; said process comprising the steps of:
- (a) reacting Mosher's acid with a compound of formula I to attach a group of the formula ##STR43## at the N-9 position of a mixture of (+) and (-) enantiomers of said compound to form a new pair of diastereoisomers; and
- (b) separating said new pair of diastereoisomers by HPLC and recovering the R,R isomer.
Parent Case Info
This is a divisional of application Ser. No. 07/742,409, filed Aug. 8, 1991; now U.S. Pat. No. 5,151,439 which is a divisional of Ser. No. 07/519,192, filed May 4, 1990 now U.S. Pat. No. 5,061,727.
US Referenced Citations (6)
Divisions (2)
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Number |
Date |
Country |
Parent |
742409 |
Aug 1991 |
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Parent |
519192 |
May 1990 |
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