Solvent-free methallylboration of ketones accelerated by tert-alcohols.

A solvent- and metal-free process has been developed for the direct methallylboration of ketones employing the stable B-methallylborinane 1, which was accelerated by tertiary alcohols. In the presence of 2.0 equiv of readily available tertiary alcohols such as tert-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.