Copper-Catalyzed Asymmetric Allylic Alkylation with Organolithium Reagents

Key words

allylic alkylation - organolithium compounds - copper - C-C bond formation

Significance

This report describes the utilization of organolithium reagents as nucleophile sources in copper-catalyzed asymmetric allylic alkylation. Using Taniaphos as the chiral ligand, various alkyllithium reagents are nicely coupled with substituted allyl bromides in S_N2′ manner. Using a chiral phosphoramidite ligand allows cinnamyl chloride and phenyllithium to participate in the reaction.

Comment

The authors proposed from ^³¹P NMR studies that the reaction passes through an intermediate state of a diphosphine copper monoalkyl species. Using ether as co-solvent stops the formation of this ­intermediate, therefore diminishes enantio­selectivity. This method tolerates a broad range of functional groups. It provides high regio- and enantioselectivity for a very general scope of allyl halides.