Treatment of o-bromophenoxide anion with sodium salts of activemethylenecompounds in the presence of copper(I) bromide in dioxane afforded benzofuran-2-one derivatives. The phenoxide group of o- and p-bromophenol activates the coupling reaction.
carbanions by copper(I) in the sub-stitution reaction toward aryl halides and allyl halides was demonstrated. Derivatives of 2(3H)-benzofuranones (2, 14 -18) were prepared in a one-pot procedure by the reaction of copper(I) diethyl malonate with sodium o-bromophenoxide. 2-Hydroxybenzofuran (4) and its 2-amino derivative (5) were obtained by using copper(I) salts of ethyl acetoacetate and ethyl cyanoacetate