Organolithium chemistry is broadly integrated and widely applied in studies that bridge inorganic, physical, organic, and theoretical chemistry.1 Reactions with organolithium species as reagents, reactants, or intermediates are so well established that organolithiums are the most widely used organometallics in contemporary organic chemistry. Deprotonative lithiations are commonly used to generate enolates, ylides, and dipole-stabilized, localized sp2 or sp or delocalized carbanions as reactive intermediates for diverse applications.2 A sequence in which a proton on a tetrahedral carbon is replaced by a substituent begins with removal of a proton from 1 to give the formally sp3 organolithium 2. Reaction of 2 with an electrophile subsequently provides 3.

Regioselective, Diastereoselective, and Enantioselective Lithiation−Substitution Sequences: Reaction Pathways and Synthetic Applications

Chiral tertiary diamines in asymmetric synthesis.

Planar-Chiral Ferrocenes: Synthetic Methods and Applications

Enantioselective desymmetrisation of achiral epoxides

Indolizidine and quinolizidine alkaloids

The deprotonation of achiral akyl carbamates with sec-butyllithium/(-)sparteine proceeds with a high degree of chiral recognition to form substituted alcohols usually with 2 95 76 ee after reaction with electrophiles followed by deprotection. The stereoselection is kinetically controlled and a qualitative transition state model is proposed. Some studies, concerning the discrimination between both enantiomers of stereogenic akyl carbamates and on its utilization for the kinetic resolution are reported. The competition between external and internal competition was investigated in few cases. Finally, we disclose a short report on the enantioselective electrophilic substitution of 1-methylindene; here the origin of stereoselection is an thermodynamically driven epimerization of diastereomeric indenyllithium sparteine complexes. INTRODUCTION Many methods for the enantioselective synthesis are based on the selection of a chiral reagent or of a reagent under the influence of a chiral catalyst between the enantiotopic faces of a trigonal carbon moiety. In only a few cases, an efficient selection between enantiotopic groups at a tetragonal carbon atom has been verified (Scheme 1). Scheme 1 Select ion between Enant iotopic Faces Select ion between Enant io top ic Groups Widely used in synthesis Impressive examples of the latter type have been reported (ref. 1) independently by the research groups of Koga and Simpkins: CSubstituted cyclohexanones are deprotonated by chiral lithium amides, derived from

I. Hoppe

Papers

Enantioselective synthesis via sparteine-induced asymmetric deprotonation

Enantioselective Synthesis via Sparteine-Induced Asymmetric Deprotonation