Patent ID: 6872856
Filing Date: 2005-03-29
Classification: C07B,C07C

Abstract:
1. A method of making an enantiomerically pure compound of the formula (I) or (II): wherein R and R′ represent C conjugate addition of an organometallic nucleophile that provides a group R as defined above to a compound of the formula (III) or (IV): wherein the conjugate addition is carried out by adding the chiral cyclopentenone of formula (III) or (IV) to an organo-Grignard reagent or to an organo-lithium reagent in the presence of a dialkylzinc or zinc chloride or a copper (I) salt or a trialkylaluminium in a solvent at a temperature from −100° C. to 0° C., and wherein X represents a leaving group to give a trans 3,4-disubstituted addition product of formula (V) or (VI) in which R and X are as previously defined; eliminating the leaving-group X from the addition product of formula (V) or (VI) to give an (R)- or (S)-4-alkyl or 4-alkenyl cyclopent-2-en-1-one of formula (VII) or (VIII) (i) hydrogenation of the compound of formula (VII) or (VIII) to give a cyclopentanone of formula (I) or (ii) conjugate addition of a second organometallic nucleophile that provides a group R′ as defined above to the compound of formula (VII) or (VIII) to give a trans 3,4-disubstituted addition product of formula (II).