Reaction of silyl enol ethers with arenediazonium salts. Part 1. α-Arylation of ketones

Abstract

α-Arylation of ketones is accomplished by the use of arenediazonium salts as aryl-cation equivalents. The reaction of silyl enol ethers with arenediazonium tetrafluoroborates proceeds in the presence of palladium(0) catalysts and tetraphenylborate anion to give α-aryl ketones in moderate yields. Alternatively, silyl enol ethers smoothly react with arenediazonium tetrafluoroborates in pyridine even without palladium catalysts and tetraphenylborate anion, affording arylated ketones in good yields. A mechanism involving addition of an aryl radical to a silyl enol ether is proposed for the latter process.