Asymmetric Catalysis of Nozaki–Hiyama Allylation and Methallylaton with A New Tridentate Chiral Ligand

Abstract

We describe the development of a new tridentate chiral ligand effective for the asymmetric catalysis of Nozaki—Hiyama allylation, methallylation and propargylation. Various aldehydes (aromatic and aliphatic) were generally allylated or methallylated with good to excellent enantioselectivity (86-96% ee). The enantioselective reaction catalyzed by this Cr-ligand complex has great potential for natural product synthesis, and a key intermediate of calcitriol lactone synthesis was obtained with excellent diastereoselectivity (97% de, 91%). Another remarkable feature of this ligand is the stability of the Cr-ligand complex which was recovered after the enantioselective reaction and recycled without diminishing the enantioselectivity and yield.