Method for Catalytic Enantioselective Alkylation of Aldehydes Using Grignard Reagents as Alkyl Sources

Alkyltitanium reagents, generated in situ from Grignard reagents and ClTi((OPr)-Pr-i)(3), can be employed without further manipulation in the enantioselective alkylation of aldehyde by the catalysis of a chiral titanium complex derived from DTBP-H-8-BINOL. The reaction is performed with good stoichiometry [1.5 equiv each of Grignard reagents and ClTi((OPr)-Pr-i)(3)] at a low catalyst loading (2 mol %), affording a variety of chiral secondary alcohols in high enantioselectivity and yields and, hence, realizing an asymmetric version of the Grignard reaction in an indirect manner.