METHOD OF SYNTHESIS OF THE SUBSTITUTED BENZOFURAN DERIVATIVES OR THEIR PHARMACEUTICALLY ACCEPTABLE SALTS Russian patent published in 1997 - IPC

FIELD: organic chemistry. SUBSTANCE: product: derivatives of the substituted benzofuran of the formula (I): where one of substituents R₁ and R₂ means hydrogen or halogen atom and other means independently of the first one amino-group or C₂-C₄-alkanoylamino-group; R₃ means hydrogen atom, direct or branched C₁-C₄-alkyl, C₁-C₄-alkoxy-group or C₂-C₄-alkoxycarbonyl-group, halogen atom or phenyl or phenyl substituted with C₁-C₄-alkyl group; A means group -(CH₂)_n-Het where Het means possibly the substituted heteromonocycle or heterobicycle containing one or two nitrogen atoms; n = 0 or whole numbers 1-3; symbol means a single or double bond. Compounds can be synthesized by a method that involves interaction of compound of the formula (II): where substituent L means a removing off group; substituent R₄ means hydrogen atom or carboxyl-protecting group with a compound of the formula (III): R′3

- C ≡ C - R′3 leading to formation of compound of the formula (IV) which then is cyclized to compound of the formula (V): . The latter is interacted with compound of the formula (VI): H₂N-A. EFFECT: improved method of synthesis.