PHOSPHINE-NICKEL(II), -COBALT(II), -PALLADIUM(0) AND -PALLADIUM(II) COMPLEXES AS CATALYSTS IN CROSS-COUPLING REACTIONS OF ARYL- AND ALKYL-GRIGNARD REAGENTS WITH ORGANIC TELLURIDES

Article abstract of DOI:10.1016/0022-328X(83)80215-0

Some alkyl- and aryl-tellurides react with Grignard reagents (RMgBr; R = aryl and alkyl) in the presence of NiCl2(PPh3)2, NiCl2(Ph2PCH2CH2CH2PPh2), or CoCl2(PPh3)2 as catalyst in THF or diethyl ether as solvent to give the cross-coupling products together with the homo-coupling products of the tellurides in good to moderate yields, with elemental tellurium being formed as a black precipitate.A catalytic reduction-oxidation cycle involving a Ni or Co complex bearing an organotellurium moiety (RTe; R = alkenyl, aryl, and alkyl) is proposed for the reaction.Palladium catalysts such as Pd(PPh3)4, PdCl2(PPh3)2, and PdCl2(PhCN)2 are revealed to be much less effective than the Ni and Co catalysts in both the yield and the stereoselectivity of the product.