Organobismuth , pentavalent

It is well established that metallic copper or copper salts efficiently catalyze N- and O-arylation reaction using pentavalent and trivalent organobismuth compounds [5-9, 24]. The C-arylation reaction of phenols and active methylene compounds using pentavalent organobismuth compounds are usually mediated by a base. However, in some cases, copper catalysts mediate C-arylation using pentavalent organobismuth compounds. 

Phenylation of terminal alkynes took place with Ph3BiF2 in the presence of Cu(I) chloride (Scheme 10) [26], Trimethylsilyl alkynes similarly worked as terminal alkynes. Other pentavalent organobismuth compounds such as Ph3BiC03 and Ph3BiCl2 were much less efficient than Ph3BiF2. Biphenyl was also formed as a by-product. It was proposed that the products were formed through reductive elimination of the intermediate Ph3Bi(C=CR1)2. 

The elementary phenylation reaction with pentavalent organobismuth reagents is itself a two-steps sequence which proceeds first by the formation of a covalent pentavalent substrate-bismuth intermediate. In the second step, this intermediate then undergoes a ligand coupling process. ... 

The first studies on the application of pentavalent organobismuth derivatives in organic synthesis focused on oxidation reactions. In the course of these studies, when Barton et al treated quinine with triphenylbismuth carbonate (5), the reaction led to a rather modest yield of the expected quininone (34%). Using an excess of the reagent (5) afforded a good yield of a mixture of diastereo-isomeric a-phenylated ketones (75%). 3... 

---