A New Sparteine Surrogate for Asymmetric Deprotonation of N-Boc Pyrrolidine

The s-BuLi complex of a cyclohexane-derived diamine is as efficient as s-BuLi/(−)-sparteine for the asymmetric deprotonation of N-Boc pyrrolidine. This is the first example of high enantioselectivity using a non-sparteine-like diamine in such reactions. The (S,S)-diamine is a useful (+)-sparteine surrogate and was utilized in short syntheses of (−)-indolizidine 167B and an intermediate for the synthesis of the CCK antagonist (+)-RP 66803.