Jm. Brown et al., STABLE ARYLPALLADIUM IODIDES AND REACTIVE ARYLPALLADIUM TRIFLUOROMETHANESULFONATES IN THE INTRAMOLECULAR HECK REACTION, Organometallics, 14(1), 1995, pp. 207-213
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).