A structural and mechanistic investigation of the mono-O-phenylation of diols with BiPh3(OAc)2

The mono-O-phenylation of enantiomerically pure pinanediol 2 using BiPh3(OAc)21 and the biphenyl-2,2′-ylenephenylbismuth analogue 9 has been investigated. It is postulated that reductive elimination at the trigonal bipyramidal bismuth (V) centre of 1 upon exposure to ambient light affects the transfer of an apical phenyl ligand to the least sterically encumbered hydroxyl group of the diol, affording the monophenyl ether in good yield. SbPh3(OAc)2 fails to undergo reductive elimination, affording the stable diolate 6 instead. The X-ray crystal structure of 6 provides a reasonable model for the intermediate of the bismuth mono-O-phenylation, and suggests further studies with bismuth complexes such as 9 possessing intramolecularly tethered ligands incapable of facilitating the mono-O-phenylation reaction. The discussions are supported by X-ray crystallographic correlations, and calculations indicate that (M)-(−)-6 adopts the lowest energy conformational diastereoisomer.