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US 5,512,689 AGranted
Process for the preparation of intermediates in the synthesis of chiral thiazolidine-2,4-dione derivatives
AssigneePfizer Inc.
InventorGeorge J. Quallich
Life of this patent
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Abstract
A process for the stereoselective preparation of intermediates in the preparation of potent, chiral thiazolidine-2,4-dione hypoglycemics.
Claims9
A process for the stereoselective preparation of a compound of formula VI, ##STR11## said compound being essentially free of its enantiomeric form;
- and said process comprising treating a ketone of formula III, ##STR12## with about 2 to 3 molar equivalents of a borane reducing agent selected from the group consisting of borane methyl sulfide complex, catecholborane and borane tetrahydrofuran, said treatment being conducted in the presence of a chiral oxazaborolidine catalyst of the formula VII, ##STR13## wherein Z is (C.sub.1 -C.sub.4)alkyl, phenyl or (C.sub.7 -C.sub.9)phenylalkyl, in a cyclic ether solvent at a temperature of about -20.degree. C. to +40.degree. C.
A process for the stereoselective preparation of a compound of formula II, ##STR14## said compound being essentially free of its enantiomeric form;
- and said process comprising treating a ketone of formula III, ##STR15## with about 2 to 3 molar equivalents of a borane reducing agent selected from the group consisting of borane methyl sulfide complex, catecholborane and borane tetrahydrofuran, said treatment being conducted in the presence of a chiral oxazaborolidine catalyst of formula VIII, ##STR16## wherein Z is (C.sub.1 -C.sub.4)alkyl, phenyl or (C.sub.7 -C.sub.9)phenylalkyl, in a cyclic ether solvent at a temperature of about -20.degree. C. to +40.degree. C.
Dependencies are inferred from the claim text.