Benzyl vinylethers have selectively been arylated at either α or β position by fine-tuned Heck-type palladium catalyses. In contrast to previous protocols, no excess of arylating reagent or substrate chelation is necessary. For achieving good yields and high α/β-selectivities various factors determining the catalytic system had to be optimized. The results of DFT computational studies correlate selectivity
Aqueous DMF−Potassium Carbonate as a Substitute for Thallium and Silver Additives in the Palladium-Catalyzed Conversion of Aryl Bromides to Acetyl Arenes
作者:Karl S. A. Vallin、Mats Larhed、Anders Hallberg
DOI:10.1021/jo015599f
日期:2001.6.1
Highly selective palladium-catalyzed internal alpha -arylations of alkyl vinyl ethers with aryl and heteroaryl bromides were conveniently conducted in aqueous DMF with potassium carbonate as base and with DPPP as bidentate ligand. The corresponding acetyl arene products were, after hydrolysis, isolated in good to excellent yields. This Heck reaction procedure does not require toxic thallium or expensive silver salt additives, is promoted by water, and is suggested to proceed via charged organopalladium intermediates. Single-mode microwave irradiation was utilized in one example to shorten the reaction time.