Synthesis of Highly Enantioenriched All-Carbon Quaternary Centers:  Conjugate Additions of Chiral Organolithium Nucleophiles to α,α-Dinitrile β,β-Disubstituted Olefins

Highly enantioenriched quaternary centers are obtained by the reaction of chiral lithiated intermediates complexed to (−)-sparteine with tetrasubstituted, α,α-dinitrile activated olefins. Lithiated N-Boc-N-Aryl benzylamine furnishes products with drs from 78:22 to 95:5, with ers exceeding 94:6. Lithiated N-Boc-N-Aryl allylamine reactants provide enecarbamate products with drs from 55:45 to 99:1, with ers ranging from 87:13 to 97:3.