Degussa Aktiengesellschaft

Degussa Aktiengellschaft

Michael Kraft

Karlheinz Drauz

Matthias Kottenhahn

Klaus Stingl

Dietrich Arntz

Gunter Prescher

Michael Schwarm

Roland Moller

Juan G Andrade

Rolf Hoffmann

Roland M&ouml;ller

The present invention is concerned with the resolution of a mixture of enantiomers of N-protected amino acids by crystallization with enantiomerically pure N-unprotected &#x3b2;-amino acid derivatives.

Process for the preparation of enantiomerically enriched amino acids

A method of isolating 1-&lsqb;N -((S)-ethoxycarbonyl)-3-phenylpropyl)-N -trifluoroacetyl&rsqb;-L-lysyl-L-proline (lisinopril (TFA) ethyl ester, LPE). The solvent or solvent mixture used for the extraction is also a main constituent of the solvent or solvent mixture from which the crystallization takes place. High yield as well as good purity of the end product are obtained, without distillation. 1-&lsqb;N -((S)-ethoxycarbonyl)-3-phenylpropyl)-N -trifluoroacetyl&rsqb;-L-lysyl-L-proline (lisinopril (TFA) ethyl ester, LPE) is described as a precursor for producing an ACE inhibitor.

1-&lsqb;N2-((S)-ethoxycarbonyl)-3-phenylproply)-N6-trifluoroacetyl&rsqb;-L-ysyl-L-proline (lisinopril (TFA) ethyl ester, LPE)

A method of isolating 1-�N.sup.2 -((S)-ethoxycarbonyl)-3-phenylpropyl)-N.sup.6 -trifluoroacetyl!-L-lysyl-L-proline (lisinopril (TFA) ethyl ester, LPE). The solvent or solvent mixture used for the extraction is also a main constituent of the solvent or solvent mixture from which the crystallization takes place. High yield as well as good purity of the end product are obtained, without distillation. 1-�N.sup.2 -((S)-ethoxycarbonyl)-3-phenylpropyl)-N.sup.6 -trifluoroacetyl!-L-lysyl-L-proline (lisinopril (TFA) ethyl ester, LPE) is described as a precursor for producing an ACE inhibitor.

Method of isolating 1-�N.sup.2

A method of producing optically active pyrrolidines of the general formula ##STR1## in which R.sup.1 is hydrogen or OH,

Method of producing optically active pyrrolidines with high enantiomeric

A method of preparation for acetals utilizing saturated or unsaturated aldehydes, in particular, the preparation of dimethylacetals of acetaldehyde, acrolein and methacrolein. The production of the acetal takes place in a liquid phase in the presence of a solid acid catalyst, such as a strongly acidic ion exchange resin or zeolite. The conversion mixture is extracted by means of water and by means of water insoluble organic solvents. There is obtained not only the desired acetals, but in addition also the unconverted initial quantities of the starting materials by a simple method and with very good yields.

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Rodenbach, Germany

Michael Kraft