1,3-Asymmetric Induction in Diastereoselective Allylations of Chiral N-Tosyl Imines.

Abstract

Lewis acid mediated allylations of β-alkoxy N-tosyl imines using allyltrimethylsilane lead to 3-alkoxy homoallylic N-tosyl amines with anti-selectivity. Two methods of Cu(OTf)2-mediated allylations are reported herein, demonstrating that diastereoselectivity can be achieved through 1,3 acyclic stereocontrol of β-chiral aldimines. Observed selectivity trends and computational evidence suggest selectivity arises through the formation of a six-membered ring chelate. The product ratios of these allylations are dependent on conformational preferences of the chelate and steric effects in the transition-state structures.