Chelation-Controlled, Palladium-Catalyzed Arylation of Vinyl Ethers.

Abstract

Chelation-controlled, palladium-catalyzed arylation of vinyl ethers with nitrogen-containing directing groups has been studied. Ethenyloxyalkylamines 1a-c and pyridines 2a-d, representing different carbon tethers were reacted with iodobenzene 4a and 1-iodonaphthalene 4b under phase-transfer conditions. The regioselectivity achieved is compared with the outcome from reactions with sterically similar vinyl ethers 3a-d. Arylations of the dimethylamine derivative 1a and the pyridine derivative 2a occurred at the terminal position of the olefins and were highly regioselective. A catalytic cycle for the regioselective, chelation-controlled vinylic substitution, involving a six-membered chelate ring, is proposed.