Direct Aldol Reaction via Dynamic Kinetic Asymmetric Transformation

Significance

The synthetic importance of the asymmetric aldol reaction can hardly be overestimated; the direct mode of the transformation is particularly useful due to the atom-economical nature of the process. However, only a limited number of protocols have been reported for the direct aldol reaction with ester donors; the substrate scope is predominantly limited to esters with α-heteroatoms and electron-withdrawing substituents. This paper reports the preparation of aldol products from aldehydes and β,γ-unsaturated esters via dynamic kinetic asymmetric transformation (DYKAT). Various types of aldehydes have been tested, including aryl, heteroaryl, alkenyl and alkyl substrates. In most cases, the reaction proceeds with excellent regio- and enantioselectivity. Notably, the DYKAT procedure has also been successfully applied to an ester containing an allenyl moiety.