Process for the preparation of pure enantiomers of R-(+)-alpha-lipoic acid and S-(-)-alpha-lipoic acid (thioctic acid), and nonene or mesyl derivatives as intermediates therefor

摘要

A multistage method for producing R-(+)- alpha -lipoic acid and S-(-)- alpha -lipoic acid (thioctic acid) by reacting a compound of formula II IMAGE II by means of enantioselective epoxidation to the epoxy alcohol of formula III, IMAGE III reduction to 1,3-diol-dihydroxynone-8-ene of formula IV, IMAGE IV reaction with a substituted sulfonic acid chloride to 1,3-disulfoxynone-8-ene of formula V, IMAGE V R = SO2CH3, SO2C6H4CH3 oxidation with ruthenium tetroxide to 6,8-disulfoxyoctanoic acid of formula VI IMAGE VI R = SO2CH3, SO2C6H4CH3 and subsequent reaction with sodium sulfide/sulfur.