Silver-Promoted Coupling of Carbon Dioxide, o-Alkynylanilines and Diaryliodonium Salts: Straightforward Access to 4-Aryloxy-2-quinolinones

A silver-promoted three-component reaction of carbon dioxide, o-alkynylanilines and diaryliodonium salts using 1,4-diazabicyclo[2.2.2]octane (DABCO) as the base has been developed for the first time, which provides an efficient and straightforward protocol for the synthesis of a wide range of 4-aryloxy-substituted 2-quinolinones in moderate to excellent yields. Diverse functional groups such as halo, trifluoromethyl, cyano and nitro are well tolerated. Mechanistic studies indicated that 4-hydroxyl-2-quinolinone generated in-situ from o-alkynylanilines and carbon dioxide might be the key intermediate for the reaction.