A bora-Brook rearrangement, i.e., the migration of boryl group from a carbon to an oxygen atom in an isolated a-boryl-substituted alkoxide, was examined, and decisive factors for the acceleration of this reaction are disclosed. In this rearrangement, the boryl-substituted alkoxide exhibited ambiphilic reactivity toward electrophiles to afford two types of products, which are electrophiles bound either at the oxygen or at the carbon atom. Using polar solvents, a saturated backbone of the boron-containing heterocycle, or larger alkali metal cations resulted in a significantly increased reaction rate of base-catalyzed isomerization of alpha-borylbenzyl alcohol including the bora-Brook rearrangement.