The Asymmetric Dialkylzinc Addition to Imines Catalyzed by [2.2]Paracyclophane-Based <i>N</i>,<i>O</i>-Ligands

Abstract

The first highly enantioselective dialkylzinc addition to imines in the presence of catalytic amounts of N,O-ligands is reported. N-formyl-alpha-(p-tolysulfonyl)benzylamines are the readily available starting materials easily obtained in a one-pot synthesis from benzaldehydes, formamide, and p-tolylsulfinic acid. Upon deprotonation, the sulfinate is eliminated to give the acyl imine. The acyl imines further react with alkylzinc reagents in the presence of catalytic amounts of [2.2]paracyclophane-based N,O-ligands L yielding the alkylated N-(1-phenylpropyl)formamides with excellent yields and enantioselectivities.