Structure-Selectivity Relationship in Alkyllithium−Aldehyde Condensations Using 3-Aminopyrrolidine Lithium Amides as Chiral Auxiliaries

A nonracemizing route to a set of chiral 3-aminopyrrolidines, based on 4-hydroxy-( l )-proline, is described. The induction potential of the lithium amides derived from these diamines has then been investigated in the asymmetric addition of alkyllithium compounds onto various aldehydes. Enantiomeric excesses up to 76% have been obtained in the case of the condensation of n -butyllithium onto o -tolualdehyde under standard experimental conditions (THF, −78 °C). Interestingly, the presence of a second asymmetric center, such as an α-methylbenzyl group, on the lateral 3-amino group gives access, according to its configuration, to one or the other of the 1- o -tolylpentan-1-ol enantiomers.