Catalytic Asymmetric Methallylation of Ketones with an (H8-BINOLate)Ti-Based Catalyst

摘要

The first catalytic asymmetric methallylation of ketones is reported. The catalyst, which is generated from titanium tetraisopropoxide, H8-BINOL, isopropanol, and tetramethallylstannane, reacts with ketones in acetonitrile to afford tertiary homoallylic alcohols in fair to excellent yields (55-99%) and fair to high enantioselectivities (46-90%). Ozonolysis of the resulting products provides access to chiral β-hydroxy ketones, which are not readily prepared from direct asymmetric aldol reaction of acetone with ketones.