Bismuth reagents secondary alcohols

The arylation of lower aliphatic alcohols was observed when the copper-catalysed decomposition of triarylbismuth diacetate was carried out in simple alcohols, used as solvent (20 mL per mmole of bismuth reagent). The yields of alkyl aryl ethers (based on the bismuth reagent) ranged from 60 to 95% for primary and secondary alcohols, but only 9% were obtained in the case of t rt-butyl alcohol.Under stoichiometric conditions, the 0-phenylation of 3-p-cholestanol by triphenylbismuth diacetate (1 equiv.) was not significantly improved upon addition of copper diacetate. 5 Different copper compounds, such as Cu(OAc)2, CuCl2, CuCl or metallic copper, can be used as effective catalysts. 

Although there is no reaction between triphenylbismuthane and copper diacetate triphenyl-bismuthane can transfer a phenyl group to alcohols and phenols when a stoichiometric amount of copper diacylate is used. When primary or secondary alcohols, used in large excess, were treated with triphenylbismuthane in the presence of copper diacetate in the ratio Ph3Bi Cu(OAc)2 =1 2, without solvent in sealed ampoules, the 0-phenyl ethers were formed in 43-91% yields (based on the bismuth reagent), at a very slow rate (several days at room temperature). No reaction with phenol was described under these conditions. ... 

Tetraphenylbismuth trifluoroacetate under neutral or slightly acidic conditions phenylates primary alcohol in reasonable yields (65-75%), but gives only moderate yields with secondary alcohols. In contrast, the reaction of bismuth [Bi(V)] reagents with alcohols under basic conditions [BTMG (2) or TMG (1)] gives, exclusively, oxidation [90]. 

Pentavalent bismuth reagents are useM for oxidizing primary and secondary alcohols to aldehydes and ketones, respectively, under very mild conditions ... 

---