A Silylborane Derivative Usable for Transition-Metal-Free Borylation

2-(Dimethylphenylsilyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (1) is a silylborane and it reacts with various aryl, alkenyl and alkyl bromides under the influence of potassium methoxide to afford the corresponding borates. In this reaction, various aryl bromides with a functional group such as a chloro, fluoro, ester or amide group can react with 1 and the bromo group is selectively substituted for the (pinacolato)boryl group. This reaction is also applicable to the substances having an allyl group because it has no need for any palladium catalyst which may remove allyl groups. Furthermore, in a case using very bulky alkyl groups such as 2, the reaction proceeds and the related boryl group substituted product is given in good yield even though it is generally difficult to introduce by conventional synthetic methods.
This reaction is a transition-metal-free reaction and environmentally benign. The given borates can be directly used for the Suzuki-Miyaura cross-coupling reaction.