| abstract |
A novel multi-step process for preparing the (4S)-enantiomer of 4-(3,4 -dichlorophenyl)-3,4-1(2H)- naphthalenone in a highly-optically pure form is disclosed. The process involved starts from the known 4-(3,4-dichlorophenyl)-4-ketobutanoic acid and proceeds through such intermediates as (1) isopropyl or tert.- butyl 4-(3,4 -dichlorophenyl)-4-ketobutanoate, (2) isopropyl or tert.-butyl 4-(3,4-dichlorophenyl)-(4R)-hydroxybutanoate, (3) isopropyl or tert.-butyl 4-(3,4-dichlorophenyl-(4R)-sulfonyloxybutanoate, (4) isopropyl or tert.-butyl 4-(3,4-dichlorophenyl)-(4R)-phenylbutanoate to finally yield the desired (4S)-4-(3,4-dichlorophenyl)-3,4-dihydro -1(2H)-naphthalenone compound in a highly-optically pure form. The latter compound, which is a (4S)-enantiomer per se, has utility as an intermediate that ultimately leads to pure cis-(1S)(4S)-N-methyl-4-(3,4-dichlorophenyl)-1,2,3,4-tetrahydro-1-naphthaleneamine (sertraline), which is a known antidepressant agent. The aforementioned isopropyl and tert.-butyl esters of 4-(3,4-dichlorophenyl)-(4R)-hydroxybutanoic acid, as well as their corresponding (4R)-methanesulfonyl, (4R)-benzenesulfonyl and (4R)-p-toluenesulfonyl derivatives, are all novel compounds, as are the aforementioned isopropyl and tert.-butyl esters of 4-(3,4-dichlorophenyl)-(4R)-phenylbutanoic acid as well as the aforesaid acid per se. These novel chiral compounds are all useful as key intermediates in the overall process of the present invention. |