Intramolecular H-Ar ligand exchange between silicon and boron: functionality transfer of Si-H to B-H.

o-C(6)H(4)(SiR(3-n)H(n))(BMes(2)) (1; R=Me, Ph; n=1, 2) undergo Mes-H (Mes=mesityl) ligand exchange between the silicon atom and the boron atom to form o-C(6)H(4)(SiMesR(3-n)H(n-1))(BMesH) (6) upon heating. The resulting hydroborane intermediates (6) immediately react with benzaldehyde to afford their corresponding benzyloxyboranes (5). A DFT study of model compounds reveals the transition states of the ligand exchange.