Heterogeneous Aquacatalytic Alkylative Cyclization of 1,6-Enynes

Significance

An alkylative cyclization of a 1,6-enyne with aryl halides (7 examples) was performed with an amphiphilic polystyrene-poly(ethylene glycol) (PS-PEG) resin-supported phosphine-palladium complex in a refluxing aqueous NaHCO₃ solution under heterogeneous conditions to give benzylidenecyclohexenes in good to high yields (63-84%). The reaction proceeded via formation of a vinylpalladium intermediate and subsequent intramolecular Heck reaction. The polymeric palladium catalyst can be readily recovered by simple filtration and recycled three times without significant loss of the catalytic activity.