Comments on the catalytic alkoxycarbonylation of alkynes

The alkoxycarbonyl complexes Pd(Ph(2)Ppy)(2)(CO2R)(OAc) where Ph(2)Ppy is 2 -pyridyldiphenylphosphine and R = Me 1, Et 2, i-Pr 3 have been prepared fro m Pd(OAc)(2) and Ph(2)Ppy in ethanol solution under an atmosphere of CO. In creasing the CO pressure favours the formation of palladium carbonyl specie s. In the presence of 2 mol equivalents of CF3CO2H, the complex Pd(Ph(2)Ppy )(2)(CO2CH3)(CF3CO2) 4 is isolated from methanol. Pd(Ph(2)Ppy)(2)-(CO2CH3)C l 5 has been obtained by the reaction of Pd(Ph(2)Ppy)(2)Cl-2 with NaOCH3 in the presence of CO. 1 and 5 have been crystallographicaly characterised as trans isomers, a geometry confirmed for all the complexes by C-13 NMR. The reactivity of the complexes toward alkynes and propadiene has been investi gated and the pi-allyl complex [Pd(Ph(2)Ppy)(2){eta(3)-C3H4C(CH3)=CH2}][O2C CF3] 8 is elated and structurally characterised.