Study of homo- and cross-coupling competition in the reaction of triarylbismuth(V) dicarboxylates with methyl acrylate in the presence of a palladium catalyst

Triarylbismuth(V) derivatives Ar3Bi(O2CR)2 (Ar = Ph, m-Tol, p-Tol; R = H, Me, Et, n-Bu, t-Bu, n-C5H11, CF3, CH2Cl, CCl3, Ph) were prepared in good to excellent yields by reaction of Ar3Bi with equimolar amounts of t-BuOOH in the presence of an acid. These compounds were tested in the C-arylation reaction of methyl acrylate, as a model substrate, in the presence of palladium catalyst (4 mol%). It was found that triphenylbismuth dicarboxylates are very active phenylating agents under mild conditions (20 °C). The effect of the carboxylic group, the effect of the nature of the palladium catalyst and the effect of oxygen on the reactivity of the organobismuth compounds and on the selectivity of the C-arylation reaction were studied. Methyl cinnamate, the C-phenylation product, and biphenyl, the homo-coupling by-product, were obtained in all cases. Triphenylbismuth divalerate Ph3Bi(O2CBu)2 is the most reactive compound among the triphenylbismuth dicarboxylates studied.

Graphical abstractAr3Bi(O2CR)2 are very active phenylating agents for the Pd-catalyzed C-arylation reaction of methyl acrylate under mild conditions. The carboxylic group, the palladium catalyst and oxygen affect the reactivity of the organobismuth compounds and the selectivity of the C-arylation reaction.Figure optionsDownload full-size imageDownload as PowerPoint slide