Chiral reductions of imines leading to the syntheses of optically active amines

摘要

A process for preparing an R enantiomer of a compound of the formula (I): IMAGE (I) wherein Ar is 3-methoxyphenyl, 3-chlorophenyl, or 1-naphthyl, and X is independently selected from the group consisting of H, F, Cl, Br, I, phenyl, CF3, CF2H, CFH2, lower alkyl (e.g., Me), O-lower alkyl (e.g., OMe), OCH2CF3, OH, CN, NO2, C(O)-lower alkyl (e.g., C(O)Me), C(O)O-lower alkyl (e.g., C(O)OMe), C(O)NH-lower alkyl (e.g., C(O)NH-Me), C(O)N-lower alkyl2 (e.g., C(O)NMe2), OC(O)-lower alkyl (e.g., OC(O)Me), and NH-C(O)-lower alkyl (e.g., NH-C(O)Me), where "lower alkyl" is selected from a group consisting of 1 to 6 carbon atoms, and m is an integer between 1 and 5, by asymmetrically and enantioselectively reducing an imine with a reducing agent/chiral auxiliary agent complex so as to produce an enantiomeric excess of R enantiomer of the compound of formula (I) over the S enantiomer of the compound of formula (I). The process is especially useful to produce compounds (R)-(+)-N-[1-(3-methoxyphenyl)ethyl]-3-(2-chlorophenyl)propanamine and (R)-(+)-N-[1-(3-methoxyphenyl)ethyl]-3-(phenyl)propanamine. Enantiomeric excess of the R enantiomer over S enantiomer of greater than 65% have been achieved.