A General, Highly Anti-Stereoselective Aldolization Method via Camphor-Derived Boryl Enolates

Camphor-derived chiral boryl enolates are highly reactive and highly anti-stereoselective enolate synthon systems in aldol addition reactions promoted by a TiCl 4 or SnCl 4 cocatalyst. More significantly, this high-yield reaction exhibits remarkable generality with respect to the aldehyde nature, as illustrated by the rapid and anti-stereoselective aldolizations with the simple saturated and unsaturated aliphatic aldehydes, and aromatic aldehydes at temperatures as low as −90 °C. The enhanced reaction generality and anti stereoselectivity of camphor-derived boryl enolates suggests the importance of the nature of chiral auxiliary architecture in determining the aldol bond construction process. Final nondestructive camphor-based auxiliary removal via hydroperoxide-mediated hydrolysis affords enantiomerically pure anti-β-hydroxy-α-methyl aldol products.