STABLE ARYLPALLADIUM IODIDES AND REACTIVE ARYLPALLADIUM TRIFLUOROMETHANESULFONATES IN THE INTRAMOLECULAR HECK REACTION

The reactions of 1-iodo-2-(3-butenyl)benzene and of two side-chain eth er analogs with hino)ferrocene](eta(2)-cyclooctatetraene)palladium gav e the expected (eta(1)-aryl)-(eta(1)-iodo)palldium adducts, the 2-oxa- 3-butenyl complex being characterized by X-ray crystallography. The al kene does not interact directly with palladium. Restricted rotation ab out the aryl-palladium bond was observed on the NMR time scale in all cases, since the methylene group(s) of the side chain were diastereoto pic. The complexes were stable, but on treatment with silver trifluoro methanesulfonate in acetone at low temperature an unstable species was identified by H-1 and P-31 NMR in two of the three cases. Spectral ob servations were consistent with the formation and subsequent rearrange ment of an intermediate along the pathway of an intramolecular Heck cy clisation with structure o-C6H4OC(CH3)(Pd[dppf]OTf).