Palladium-Catalyzed Oxidative Cyclization of 1,5-Dienes -- a Mechanistic Investigation.

Abstract

Nucleophilic attack of acetate ion on an olefinic bond of dichloro (η 4 -cis-1,2-divinylcyclohexane) palladium has been shown by NMR spectroscopy to lead to a σ,π-palladium (II) complex. This complex, which is also formed from nucleophilic attack on cis-1,2-divinylcyclohexane in the presence of palladium (II) acetate, spontaneously undergoes migratory insertion of the remaining olefinic bond into the palladium-carbon σ bond. This is followed by β-elimination to yield (1R*, 6S*, 7S*)-7-acetoxy-9-methylenebicyclo [4.3.0] nonane together with some rearranged products. The insertion has been shown to be favored by acidic reaction conditions