METHOD OF PRODUCING ETHERS OF SUBSTITUTED 5,6-DICYANOBENZOFURAN-2-CARBOXYLIC ACIDS Russian patent published in 2012 - IPC C07C67/00 C07D307/84 C07D307/78 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing ethers of substituted 5,6-dicyanobenzofuran-2-carboxylic acids of general formula: , where a R=4-CH₃C₆H₄; b R=4-CH₃O-C₆H₄; c R=2-thienyl; R₁=CH₃, C₂H₅, which can be used as precursors for producing biologically active substances, fluorescent materials and for synthesis of phthalocyanines. The method involves production of ethers of substituted 5,6-dicyanobenzofuran-2-carboxylic acids based on reaction of 4-bromo-5-nitrophthalonitrile and sodium salts of 2,4-dioxobutanoic acid derivatives, where reaction of said reagents takes place at temperature 75…85°C and molar ratio 1:2, respectively, for 18-24 hours in a dimethyl formamide solution, and the reaction mass is then diluted with ten-fold excess water at temperature T=0…25°C. The resinous residue is extracted with methylene chloride, thoroughly washed with water and chromatographed on silica gel. The eluent (solvent) is evaporated and the precipitate is filtered and recrystallised from alcohol.

EFFECT: high efficiency of the method.

1 cl, 1 tbl, 3 ex