Palladium-Catalyzed Dimerization of Vinyl Ethers to Acetals

摘要

(α-Diimine)PdCI+ species catalytically dimerize alkyl and silyl vinyl ethers to β,γ-unsaturated CH_2=CHCH_2CH(OR)_2 acetals, and they cyclize divinyl ethers to analogous cyclic acetals. A plausible mechanism comprises in situ generation of an active PdOR alkoxide species, double vinyl ether insertion to generate Pd{CH_2-CH(OR)CH_2CH(OR)_2} species, and β-OR elimination to generate the acetal product. In the presence of vinyl ethers, (α-diimine)PdCl~+ species can be used to initiate ethylene polymerization.