C. Fehr et al., HIGHLY ENANTIOSELECTIVE PROTONATION OF THIOL ESTER ENOLATES, Angewandte Chemie, International Edition in English, 32(7), 1993, pp. 1042-1044
Impressive enantiomer excesses of 99% were achieved in the protonation
of thioester enolate 2, prepared from racemic 1, with the chiral prot
on sources (-)- and (+)-N-isopropylephedrine ((-)-3 and (+)-3). This l
arge-scale procedure allows access to many enantiopure terpenoids.