A new catalytic method for the synthesis of boroxanes

A new Ru–H complex catalyzed O-borylation of boronic acids with vinylboronates leading to boroxane bond formation with evolution of ethylene is described. Under the optimum conditions, when [Ru(CO)Cl(H)(PPh3)3] and excess vinylboronate are used, the reaction gives exclusively the corresponding boroxane in high yield. The proposed mechanism of catalysis is supported by the results of the equimolar reaction of Ru–B complex with 1,3,2-dioxaborinan-2-ol.