| abstract |
A process for preparing the R- or S-isomer of a trisubstituted ethane of formula 2 wherein Ar, R.sup.3 is. and R.sup.4, which may be the same or different, are each C.sub.6-12.n. a monocyclic or bicyclic aryl group, C.sub.1-9.n. a monocyclic or bicyclic heteroaryl group which may be substituted, an Aux is a radical of a cyclic or acyclic sultam, an alcohol or an amine containing one or more homochiral centers, and the wavy line means that the -CH (R.sup.3) configuration is either R 1 or S, in which it reacts the olefin of formula 1, wherein Ar, R 5, R 4. and Aux are as defined above, with an organometallic reagent containing the moiety R.sup.3. as defined above, and the resulting intermediate is cleaved by treatment with a thiol of the formula RSH wherein R is C 1-7 alkyl or C 1-6 alkyl. aryl C.sub.1-3.n. alkyl, in the presence of a base, to yield a thioester, which decarbonylation yields the desired R- or S-isomer of formula 2. Also included are alpha, .beta.-unsaturated olefins as intermediates. |