Kinetic Resolution of Tertiary Allylic Alcohols: Highly Enantioselective Access to Cyclic Ethers Bearing an α-Tetrasubstituted Stereocenter.

A chiral phosphoric acid-catalyzed kinetic resolution of tertiary allylic alcohols was developed to provide structurally valuable enantioenriched 2,2-disubstituted tetrahydrofurans, tetrahydropyrans, and oxepane. A variety of tertiary allylic alcohols were resolved with selectivity factors of ≤120. A tertiary allylic carbocationic intermediate mediates the enantioselective intramolecular substitution to achieve high regio- and enantioselectivity. A gram-scale reaction with low catalyst loading and subsequent transformations of the recovered alcohols and products demonstrated the utility of this method.