8-CHLORO-6-SULFONYLHYDROXYOCTANOIC ACIDS AND METHOD OF THEIR SYNTHESIS, THEIR ESTERS AND METHOD OF THEIR SYNTHESIS, 6,8-DICHLOROOCTANOIC ACID ESTERS AND METHOD OF THEIR SYNTHESIS, METHOD OF SYNTHESIS OF 6,8-DICHLOROOCTANOIC ACIDS AND METHOD OF SYNTHESIS OF α-LIPOIC ACID (VERSIONS) Russian patent published in 2001 - IPC

FIELD: organic chemistry, chemical technology. SUBSTANCE: invention relates to method of synthesis of 8-chloro-6-sulfonylhydroxyoctanoic acids of the formula (I) α and, respectively, their alkyl esters of the formula (II) and 6,8-dichlorooctanoic acid and, respectively, its alkyl esters of the formula (III) as intermediate compounds in synthesis of enantiomers of -lipoic acid also and methods of conversion of enantiomers of 6-chloro-8-hydroxyoctanoic acid to enantiomers of α-lipoic acid. Method of synthesis of α-lipoic acid involves esterification of 8-chlorohydroxyoctanoic acid to yield alkyl esters that are subjected further for reaction with sulfonyl chloride and tertiary nitrogen base and 8-chloro-6-sulfonylhydroxyoctanoic acid alkyl esters are obtained followed by their interaction with alkaline metal disulfides/sulfur and conversion to dihydrolipoic acid and the latter is oxidized to yield α-lipoic acid. The present method using new intermediate compounds provides to synthesize enantiomer of α-lipoic acid with theoretical yield 100%. EFFECT: improved method of synthesis. 18 cl, 18 ex