Reactions of palladium(II) with organic compounds. Part I. Oxidative cyclisation of 3-methyl-3-phenylbut-1-ene and 3,3,3-triphenylpropene

Abstract

The olefins PhR₂C·CH:CH₂(R = Ph or Me) undergo oxidative cyclisation to give the corresponding 1,1-disubstituted indenes when treated with palladium(II) acetate in acetic acid at 80°. Evidence is adduced that reaction does not occur via the expected oxypalladation adducts and that little or no carbonium-ion character is generated in the olefinic carbon skeleton during reaction. The probable pathway involves a relatively slow intramolecular electrophilic aromatic substitution within a π-olefin complex.