Conversion of One Hydroxy Group in a Diol to a Phenyl Ether with Triphenylbismuth Diacetate, a New Glycol Reaction Showing Strong Axial Preference in Six-Membered Rings

Article abstract of DOI:10.1021/jo00152a007

After being refluxed for a few hours, a dichloromethane solution of a diol with triphenylbismuth diacetate gave in most cases excellent yields of a monophenyl ether.No diphenylated products were found.Tertiary hydroxy groups were only phenylated in bis tertiary diols, and then in poor yield.Increasing the distance between the hydroxy groups up to six carbon atoms decreased the speed of the reaction which nevertheless was still preparatively useful.Diols in flexible rings behaved like their acyclic counterparts.The course of the reaction was also examined with someconformationally rigid molecules: trans-4-tert-butyl-cis-2-hydroxycyclohexanol, trans-4-tert-butyl-trans-2-hydroxycyclohexanol, cholestane-2α,3α-diol, cholestane-2α,3β-diol, and pyranoside derivatives with the α-D-gluco, α-D-manno, α-D-galacto, and α-D-allo configurations.The phenylations of cis-diols were strongly regioselective for axial epimers, while those of trans, bis equatorial diols were undiscriminate and often much slower.A feasible general mechanism is proposed to explain these results.