A Room-Temperature Catalytic Asymmetric Synthesis of Allenes with ECNU-Phos

Abstract

Three-carbon axial chirality has been asymmetrically established from racemic one-carbon central chirality efficiently at room temperature: we report here the discovery of the first catalytic asymmetric carbonylation of readily available racemic propargylic carbonates to access optically active 2,3-allenoates with fairly high ee. The combination of [(π-allyl)PdCl]2 with [(R)-ECNU-Phos], a new chiral bisphosphine ligand based on a biphenyl skeleton, demonstrates high enantioselectivity. Both enantiomers of allenoates can be obtained at room temperature by applying either (R)- or (S)-ECNU-Phos.