Acyclic Stereocontrol of Free Radical Reactions Involving Alkyl 2-(1-Hydroxyalkyl)propenoates

Abstract

The addition of cyclohexyl and t-butyl free radicals to silylated derivatives of alkyl 2-(1-hydroxyalkyl) propenoates was found to be stereoselective . In the case of the cyclohexyl radical the stereoselectivity was dependent upon the conditions used to generate the free radical and to quench the intermediate. Stereoselectivity in additions of the t-butyl radical was found to be temperature-dependent. In all cases stereoselectivity increased as the steric bulk of the group attached to the carbinol oxygen increased. A simple model which accounts for the stereoselectivity is proposed.