CARBONYLATION OF ARYL- AND VINYL-TELLURIUM COMPOUNDS WITH CARBON MONOXIDE IN THE PRESENCE OF PALLADIUM(II) SALTS

Article abstract of DOI:10.1016/0022-328X(87)80121-3

Aryl- and vinyl-tellurium(II or IV) compounds react with carbon monoxide (CO) in suitable organic solvents to give the corresponding carboxylic acids in moderate to quantitative yields in the presence of a stoichiometric amount of a palladium(II) salt.Treatment of (Z)-styrylphenyl telluride with atmospheric pressure of CO at room temperature in the presence of palladium(II) chloride or lithium chloropalladate(II) affords predominantly (E)-cinnamic acid, while in the presence of palladium(II) acetate similar reaction gives the (Z)-acid highly selectively.Under higher CO pressures (5-50 atm), however, the (Z)-acid becomes the major product, even when palladium(II) chloride is used.The following pathways are proposed for this carbonylation: (1) in the first step organotellurium compounds form the monomeric and/or dimeric palladium complexes such as <(R2Te)PdCl2>2 and/or (R2Te)2PdCl2 (R = aryl, vinyl), then (2) the migration of R moiety from tellurium to palladium (transmetallation) occurs to afford the reactive aryl- or alkenyl-palladium compounds, and (3) the compounds react with CO to give the corresponding acylpalladium compounds, after alkaline hydrolysis, the carboxylic acids are formed.The presence of an ionic carbene-like organopalladium complex is proposed for the formation of the (E)-acid from (Z)-telluride.