Asta Medica, Aktiengesellschaft

Arzneimittelwerk Dresden Gmbh

Gunter Laban

Rainer Gewald

Thomas Beisswenger

Matthias Rischer

Karl-Friedrich Landgraf

Eberhard Oestreich

The invention relates to a process for the preparation of compounds of the general formula I

Process for the preparation of enantiomerically pure 3-hydroxyoctanedioic acid diesters by asymmetric catalytic hydrogenation

The invention relates to a process for the preparation of compounds of the general formula I ##STR1## in which R.sup.1 and R.sup.2 are identical or different and are a C.sub.1 -C.sub.20 -alkyl group, C.sub.3 -C.sub.12 -cycloalkyl group, C.sub.7 -C.sub.12 -aralkyl group or a mono- or binuclear aryl group, in which a ketone of the formula III or IV ##STR2## in which R.sup.1 and R.sup.2 have the above meaning, is asymmetrically hydrogenated.

Process for the preparation of enantiomerically pure

The invention is relative to a thioctic acid with a predominant amount of an enantiomer and a novel modification, in the case of which the X-ray powder diffractograms show a characteristic reflex in the range of 23.4 to 22.7.degree. 2 theta(Cu) which shifts in the direction of the smaller angular values as the enantiomer content increases.

Alpha-lipoic acid with novel modification

The invention relates to (+) and (-)-8-halogen-6-hydroxy-octanoic acid enantiomers wherein the halogen is Cl, Br, or I, and their respective preparatory processes.

(+)- and (-) -8-halogen-6- hydroxy-octanoic acid its salts and esters

(+)- or (-) -8-halogen-6-hydroxy-octanoic acid, its salts and esters,

The synthesis of pure enantiomers of 8-chloro-6-sulfonyloxy-octanoic acids and their alkyl esters and of pure enantiomers of 6,8-dichloro-octanoic acid and its alkyl esters as intermediates for the synthesis of the enantiomers of .alpha.-liponic acid as well as a method for converting the two enantiomers of 8-chloro-6-hydroxy-octanoic acid into an enantiomer of .alpha.-liponic acid.

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Langebruck, Germany

Gunter Laban