Process for resolution of racemic DL-.alpha.-aminocarboxylic acids
AssigneeRiedel-de Haen Aktiengesellschaft
InventorsWolfgang Dannenberg, Horst Schmand
Life of this patent
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Abstract
In a process for resolving racemic DL-.alpha.-aminocarboxylic acids the said acids are reacted in an inert solvent with an aromatic o-hydroxy aldehyde to obtain an azomethine derivative which is reacted in the same stage with an optically active amine base to give a salt. The diastereomeric salt obtained is separated and the respective optically active .alpha.-aminocarboxylic acid is obtained therefrom by an acid treatment. By this process aliphatic and aromatic .alpha.-amino-carboxylic acids can be resolved, especially p-hydroxyphenyl glycine.
Claims23
A process for resolving a racemic DL-.alpha.-aminocarboxylic acid of the formula ##STR4## in which R is isopropyl, phenyl, p-hydroxyphenyl or benzyl, which comprises
- (a) in a medium selected from the group consisting of inert solvents and mixtures thereof, reacting said DL-.alpha.-aminocarboxylic acid with an aromatic aldehyde of the formula ##STR5## in which R.sub.1 and R.sub.2, which are identical or different, each is hydrogen or halogen, to form an azomethine derivative and in the same reaction stage reacting the azomethine derivative with an optically active tertiary amine having a dissociation constant of from 10.sup.-9 to 10.sup.-12 to form a mixture of diastereomeric salts;
- (b) separating the mixture by crystallization into its component diastereomeric salts;
- and
- (c) liberating an optically active .alpha.-aminocarboxylic acid by treating a separated salt with a strong acid.
A process for resolving a racemic DL-.alpha.-aminocarboxylic acid of the formula ##STR7## in which R is isopropyl, phenyl, p-hydroxyphenyl or benzyl, which comprises
- (a) in a medium selected from the group consisting of inert solvents and mixtures thereof and at a temperature in the range of from 0.degree. C. to the boiling temperature of said medium and while stirring for a period of from 1 to 160 hours, reacting said DL-.alpha.-aminocarboxylic acid with an aromatic aldehyde of the formula ##STR8## in which R.sub.1 and R.sub.2, which are identical or different, each is hydrogen or halogen, to form an azomethine derivative and in the same reaction stage reacting the azomethine derivative with an optically active tertiary amine having a dissociation constant of from 10.sup.-9 to 10.sup.-12 to form a mixture of diastereomeric salts;
- (b) separating the mixture by crystallization into its component diastereomeric salts;
- (c) liberating an optically active .alpha.-aminocarboxylic acid by treating a separated salt with a strong acid.
A process for resolving a racemic DL-.alpha.-aminocarboxylic acid of the formula ##STR9## in which R is isopropyl, phenyl, p-hydroxylphenyl or benzyl, which comprises
- (a) in a medium selected from the group consisting of inert solvents and mixtures thereof and at a temperature in the range of from 0.degree. C. to the boiling temperature of the reaction medium and without removal of the water set free during reaction, reacting DL-.alpha.-aminocarboxylic acid with an aromatic aldehyde of the formula ##STR10## in which R.sub.1 and R.sub.2, which are identical or different, each is hydrogen or halogen, to form an azomethine derivative and in the same reaction stage reacting the azomethine derivative with an optically active tertiary amine having a dissociation constant of from 10.sup.-9 to 10.sup.-12 to form a mixture of diastereomeric salts;
- (b) separating the mixture by crystallization into its component diastereomeric salts;
- (c) liberating an optically active .alpha.-aminocarboxylic acid by treating a separated salt with a strong acid.
A compound of the formula ##STR11## in which A.sup..sym. is a cation formed by addition of a proton to the nitrogen atom of an optically active tertiary amine having a dissociation constant of from 10.sup.-9 to 10.sup.-12, and in which R is isopropyl, p-hydroxyphenyl or benzyl.
A compound which is the salt of d-N-methyl ephedrine and N-salicyliden-p-hydroxyphenyl glycine.
A compound which is the salt of l-N-methyl ephedrine and N-salicyliden-p-hydroxyphenyl glycine.
A compound which is the salt of d-N-methyl ephedrine and N-salicyliden-phenyl glycine.
A compound which is the salt of l-N-methyl ephedrine and N-salicyliden-phenyl alanine.
A compound which is the salt of d-N-methyl ephedrine and N-salicyliden-valine.
A compound which is the salt of l-N-methyl ephedrine and N-salicyliden-valine.
A compound which is the salt of d-1-phenyl-2-dimethylaminopropane-1,3-diol and N-salicyliden-hydroxyphenyl glycine.
A compound which is the salt of l-1-phenyl-2-dimethylaminopropane-1,3-diol and N-salicyliden-p-hydroxyphenyl glycine.
Dependencies are inferred from the claim text.