Palladium(0)-alkene bis(triarylphosphine) complexes as catalyst precursors for the methoxycarbonylation of styrene

The fluorous complex [Pd(0)(P{C6H4 p-SiMe2(CH2CH2C6F13)}(3))(2)(MA)] (MA = maleic anhydride) was synthesized and characterized by its NMR spectra. Together with the nonfluorous complexes [Pd(0)(PPh3)(2)(alkene)] (alkene = C2H4, (NC)(2)C=C(CN)(2), NCC(H)= C(H)CN, MA, or benzoquinone) these were evaluated as catalyst precursors in the methoxycarbonylation of styrene. The nonfluorous C2H4 and MA complexes gave the highest conversions (the turnover number (TON) was 120; the (average) turnover frequency (TOF) amounted to 80 h(-1)). The fluorous complex gave a significantly lower conversion (TOF) about 38; TOF 26 h(-1)) than its nonfluorous counterpart, which is caused by a lower stability of the fluorous complex under the reaction conditions.