Organobismuth(V)-Mediated O-Phenylation of Sterically Hindered Alcohols

Significance

The formation of unsymmetrical ethers bearing an aryl and a sterically hindered alkyl moiety is a difficult task. A nucleophilic attack of phenolates to sterically hindered alkyl halides is either not possible or too slow. The Pd-catalyzed reaction between aryl halides and sterically hindered alcohols requires the presence of strongly basic nucleophiles such as alkoxides. In this article a new organobismuth(V)-mediated O-phenylation protocol is presented: Tetraphenylbismuth fluo­ride (Ph₄BiF) is used as phenylating agent along with a catalytic amount of copper(II) acetate and Cy₂NMe as base. The reaction proceeds smoothly at room temperature yielding the respective phenyl ethers of highly sterically hindered alcohols, such as tert-butanol or adamanthan-1-ol, in good to excellent yields. Moreover, the method was extended to the phenylation of sterically hindered alcohols which cannot be prepared with protocols involving harsher conditions, such as high temperatures or strong bases.