Titanium-Catalyzed Asymmetric Alkylation of Aldehydes Using Trialkylboranes

Abstract

A catalytic asymmetric titanium(IV)-catalyzed alkylation of aldehydes using trialkylboranes is described. Good yields and enantioselectivities are seen for aromatic and unsaturated aldehydes, though reactions with aliphatic alde-hydes are lower-yielding and heteroaryl aldehydes give lower enantioselectivities. For the related asymmetric alkylation of aldehydes using Grignard reagents see: Y. Maramatsu, T. Harada Angew. Chem. Int. Ed. 2008, 47, 1088.