4,4,5,5‐Tetraphenyl‐1,3,2‐dioxaborolane: A Bulky Borane for the Transition Metal Catalysed Hydroboration of Alkenes

Abstract 4,4,5,5‐Tetraphenyl‐1,3,2‐dioxaborolane (HBBzpin, 3) has been prepared in high yield by the addition of H3B·SMe2 to benzopinacol. HBBzpin is a relatively stable solid that reacts with a variety of alkenes under catalytic conditions to give air‐ and chromatography‐stable organoboronate esters. Reactions of vinylarenes in the presence of catalytic amounts of [Cp*IrCl2]2 gave the corresponding terminal products selectively. Addition of HBBzpin to RhCl(PPh3)3 gave Rh(H)Cl(BzBpin)(PPh3)2 (11) as the only new rhodium‐containing product. The complex 11 has been characterized by a number of physical and analytical methods, including a single‐crystal X‐ray diffraction study. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)