Process for preparing ketone enantiomer
US5196607A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 14, 1992 |
| Grant date | Mar 23, 1993 |
| Priority date | — |
| Expiry date | Feb 14, 2012 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C51/487
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
A novel multi-step process for preparing the (4S)-enantiomer of 4-(3,4-dichlorophenyl)-3,4-dihydro-1(2H)-naphthalenone in a highly-optically pure form is disclosed. The process involves (1) first reacting 3,4-dichlorocinnamyl chloride with L-(-)-ephedrine in a chlorinated lower hydrocarbon solvent to form the corresponding chiral N-methyl-N-(.beta.-hydroxy-.beta.-phenylisopropyl)-3-(3,4-dichlorophenyl)p ropenoamide; (2) then subjecting the chiral .alpha.,.beta.-unsaturated amide formed in the first step to a Grignard reaction with phenyl magnesium chloride or bromide, followed by hydrolysis, to effect a conjugate addition of the phenyl group and the hydrogen element to the aforesaid .alpha.,.beta.-unsaturated propenoamide and so selectively form the corresponding chiral N-methyl-N-(.beta.-hydroxy-.beta.-phenylisopropyl)-3-(3,4-dichlorophenyl)- 3-phenylpropanoamide; (3) hydrolyzing the aforesaid chiral 3-phenylated propanoamide compound to yield the corresponding 3-(3,4-dichlorophenyl)-(3R)-propanoic acid; (4) next esterifying the stereospecific (3R)-phenylated propanoic acid obtained in the third step with an appropriate lower alkanol in the presence of thionyl chloride or a lower …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.