Reversible cyclobutane formation in a palladium-mediated reaction; the X-ray structure of {2–4-η-(1,2,3,4,5-pentamethyl-6R-phenylbicyclo[3,2,0]hept-2-enyl)}pentane-2,4-dionatopalladium

Abstract

The σ,η-complex (I) undergoes spontaneous reversible ring closure to give the endo-phenyl allylic complex(VII), as well as an irreversible ring closure to the thermodynamically most stable exo-phenyl allylic isomer (III); the crystal structure of (VIII), the pentanedionato-derivative of (VII), is reported.