Asymmetric Lithiation−Substitution Sequences of Substituted Allylamines

(−)-Sparteine-mediated asymmetric lithiation−substitution sequences of 2- and 3-substituted
N-(Boc)-N-(p-methoxyphenyl) allylic amines with electrophiles have been investigated. Asymmetric
lithiation−substitutions of N-(Boc)-N-(p-methoxyphenyl) allylic amines 11, 12, 13, 14, and 15 provide
highly enantioenriched enecarbamates in good yields. Further transformations to give aldehydes,
acids, ketones, and a Diels−Alder adduct are reported. The 1,4-addition products from reactions of
the lithiated allylic amines from 14 and 15 with conjugated activated alkenes gives enecarbamates
with two and three stereogenic centers in good yields with high diastereomeric and enantiomeric
ratios. Synthetic transformation of these products by acid hydrolysis and subsequent cyclization
provide stereoselective access to bicyclic compounds containing four and five stereogenic centers
with high diastereoselectivity and enantioselectivity. It is suggested that allyllithium complexes
generated by asymmetric deprotonation react with most electrophiles with inversion of configuration.