Solvent-Free Methallylboration of Ketones Accelerated by <i>tert</i>-Alcohols

A solvent- and metal-free process has been developed for the direct methallylboration of ketones employing the stable <i>B</i>-methallylborinane <b>1</b>, which was accelerated by tertiary alcohols. In the presence of 2.0 equiv of readily available tertiary alcohols such as <i>tert</i>-amyl alcohol, the methallylation products were prepared at room temperature in excellent yields. The salient features of the described process include simple operation, high efficiency, and mild reaction conditions.