Asymmetric deprotonation with alkyllithium‐(–)‐sparteine

Overview of Carbanion Dynamics and Electrophilic Substitutions in Chiral Organolithium Compounds

“…Recent years have seen numerous examples of butyllithium (BuLi) or sec -butyllithium ( s -BuLi) complexed with a chiral ligand, to create a chiral base that is able to effect enantioselective deprotonations by distinguishing enantiotopic protons. 1,4,5,14,15 The chapter by Kizirian in this volume details the use of organolithium bases such as the alkyllithiums that are coordinated to chiral diamine ligands.…”

Navigating the Chiral Pool in the Total Synthesis of Complex Terpene Natural Products

“…Overall, only 8 linear steps were required to access this complex diterpene, magnificently showcasing the synthetic utility of lithiated carbamates in organic synthesis. 217,218 …”

“…In the final step, 176 was converted into (+)-vigulariol via Wittig olefination. Overall, only eight linear steps were required to access this complex diterpene, magnificently showcasing the synthetic utility of lithiated carbamates in organic synthesis. , …”

Synthetic Applications and Inversion Dynamics of Configurationally Stable 2-Lithio-2-arylpyrrolidines and -piperidines

“…6 Such low barriers indicate a high degree of configurational instability of benzylic organolithiums (half-life for inversion ≤10 minutes), which provides a challenge to stereoselective synthesis. 7 Approaches to lithiation/alkylation sequences at benzylic sites often employ chiral auxiliaries 8 or chiral ligands such as (−)-sparteine 9 or a bisoxazoline 7e, 10 to impose configurational stability in the ground state or diastereomeric bias in the transition state, thus leading to diastereomerically or enantiomerically enriched products. Many years ago, the necessity of diastereomeric bias in the alkylation of a benzylic dipole-stabilized α-aminoorganolithium compound was demonstrated by Meyers, who showed that an enantioenriched tertiary tetrahydroisoquinoline formamidine (97:3 er), in which the lithium was also intramolecularly chelated, produced racemic product after a lithiation-substitution sequence in THF at −100 °C.…”