ENANTIOSELECTIVE SYNTHESIS VIA SPARTEINE-INDUCED ASYMMETRIC DEPROTONATION

The deprotonation of achiral alkyl carbamates with sec-butyllithium/(- )-sparteine proceeds with a high degree of chiral recognition to form substituted alcohols usually with greater-than-or-equal-to 95 % ee aft er reaction with electrophiles followed by deprotection. The stereosel ection is kinetically controlled and a qualitative transition state mo del is proposed. Some studies, concerning the discrimination between b oth enantiomers of stereogenic alkyl carbamates and on its utilization for the kinetic resolution are reported. The competition between exte rnal and internal competition was investigated in few cases. - Finally , we disclose a short report on the enantioselective electrophilic sub stitution of 1-methylindene; here the origin of stereoselection is an thermodynamically driven epimerization of diastereomeric indenyl-lithi um sparteine complexes.