METHOD OF SYNTHESIS OF PURE ISOFLAVONE DERIVATIVES Russian patent published in 1995 - IPC

FIELD: organic chemistry. SUBSTANCE: method involves synthesis of pure isoflavone derivatives of the formula (I) given in description where R - hydrogen or isopropyl; R₂ and R₃ - hydrogen or C₁-C₂-alkoxy-group. Synthesis is carried out by cyclization of resorcinol derivative of the formula (II) given in description with ethyl-ortho-formate at 70-100 C (preferably at 80-90 C) in the presence of organic solvent (preferably in dimethylformamide and/or isopropanol) at 0.3-2-fold quantity with respect to measured volume of resorcinol derivatives of the formula (III) given in description, and/or in the presence of ethyl-ortho-formate excess for preparing 20-70% supersaturated solution of product of the formula (III). The latter is isolated continuously from the mixture following by cooling of reaction mixture and separation of compound of the formula (II) by filtration where R₁ - hydrogen; R₂ and R₃ - see above, and/or by addition of nonpolar or polar solvent to reaction mixture with selective dissolving of formed by-side product of the formula (V) given in description where R₁ - hydrogen; R₂ and R₃ - see above, and/or addition of almost equivalent quantity of anhydrous potassium carbonate to reaction mixture and isolation of crystallized out double salt of the formula (IV) given in description where R₂ and R₃ - see above. Then compound of the formula (IV) or (I) where R₁ - hydrogen is alkylated with haloidalkyl, and the end pure product of the formula (I) is isolated where R₁ - isopropyl and containing not more 0.5% polluting impurity of compound of the formula (V). Double salt is formed after addition of nonpolar solvent (preferable toluene) and anhydrous potassium carbonate at 40-80 C (preferably at 60 C). Ethanol formed in cyclization reaction is remained in reaction medium. Purity of the end product is above 99.8% . Synthesized compounds were used in medicine. EFFECT: improved method of synthesis. 4 cl