Process for the preparation of N-substituted glycine acids or gl

Details Process for the preparation of N-substituted glycine acids or gl Process for the preparation of N-substituted glycine acids or gl

1996-06-05

1997-11-11

Richter, Johann

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

548459, 548492, C07B 702, C07B 704, C07D20936, C07D20942

Patent

active

056866259

DESCRIPTION:

BRIEF SUMMARY
This application is a 371 of PCT/EP 94/04259 filed Dec. 21, 1994.
Indigo has been prepared worldwide for a long time from N-phenylglycine, which is oxidized via indoxyl to give indigo. According to Ullmann, volume A 14, 149 to 156; the N-phenylglycine needed for this is prepared essentially either by reaction of monochloroacetic acid with aniline or anthranilic acid or by hydrolysis of N-cyanomethylaniline. For preparation of N-cyanomethylaniline, hydrocyanic acid or sodium cyanide is reacted with dianilinomethane here. However, working with monochloroacetic acid or with cyanides is undesirable for safety and environmental protection reasons.
It has now been found, unexpectedly, that indoxyl can be prepared not only from N-phenylglycine but also from N-phenylglycine esters, and that N-substituted glycine esters and also N-substituted glycine acids can be prepared by an environment-friendly route by reaction of an amine with a glyoxylic acid ester half-acetal (hemiacetal) or a glyoxylic acid half-acetal. Glyoxylic acid eater half-acetals and glyoxylic acid half-acetals (hemiacetal) can be produced on a large industrial scale by an environment-friendly route by ozonolysis of maleic acid derivatives and hydrogenation of the peroxidic reaction solution, for example in accordance with U.S. Pat. No. 5,015,760.
The invention therefore relates to a process for the preparation of N-substituted glycine acids or glycine esters of the formula to 10 C atoms and R.sub.1 and R.sub.2 independently of one another are hydrogen, a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group where R.sub.1 and R.sub.2 are not simultaneously hydrogen, which comprises reacting a glyoxylic acid ester half-acetal or glyoxylic acid half-acetal of the formula having 1 to 4 C atoms, with an amine of the formula at temperatures from 0.degree. C. up to the reflux temperature of the diluent used, and treating the reaction product with hydrogen under pressure in the presence of a hydrogenation catalyst and a diluent, the N-substituted glycine ester or the N-substituted glycine acid of the formula I being formed, and, if desired, isolating this from the reaction mixture and if appropriate converting it into a salt or, in the case of the glycine ester, into the free acid.
In the formulae I to III, R is hydrogen or a straight-chain or branched alkyl group having 1 to 10 C atoms, preferably having 1 to 4 C atoms, especially preferably having 1 or 2 C. atoms, and R.sub.3 is an alkyl group having 1 to 4 C atoms, preferably having 1 or 2 C atoms, where R and R.sub.3 particularly preferably have the same meaning. R.sub.1 and R.sub.2 independently of one another are hydrogen, an alkyl group or an aryl group, where R.sub.1 and R.sub.2 are not simultaneously hydrogen. Alkyl group here is to be understood as a straight-chain, branched or cyclic alkyl group having 1 to 22 C atoms, which can be unsubstituted or substituted by alkoxy groups having 1 to 4 C atoms or by phenyl groups, for example the methyl, ethyl, n-propyl, butyl, octyl, dodecyl or hexadecyl group or isomers thereof, such as iso-propyl, iso-butyl, 2-ethylhexyl or iso-dodecyl groups, or benzyl or ethylphenyl groups. Alkoxy groups are, for example, methoxy, ethoxy, butoxy or iso-butoxy groups. An aryl group is a phenyl or naphthyl group which is unsubstituted or substituted by halogen, by alkyl groups, preferably having 1 to 6 atoms, particularly preferably having 1 to 4 C atoms, or by alkoxy groups, preferably having 1 to 4 C atoms, a phenyl group being preferred. Halogen is fluorine, chlorine or bromine. Preferably, R.sub.1 is hydrogen and R.sub.2 is an aryl group, preferably a phenyl or naphthyl group which is unsubstituted or substituted by halogen, by alkyl groups having 1 to 4 C atoms or by alkoxy groups having 1 to 4 C atoms, particularly preferably a phenyl or naphthyl group which is unsubstituted or substituted by alkyl groups.
The preferred N-substituted glycine acids and glycine esters accordingly include compounds of the formula ##STR1## in which R has

REFERENCES:
patent: 3073821 (1963-01-01), Johl et al.
patent: 4073804 (1978-02-01), Hearon et al.
patent: 5015760 (1991-05-01), Sajtos
Chemical Abstracts, vol. 99, Abstract No. 99:5513y (1983).
Pfeiffer et al., Liebigs. Ann. Chem., pp. 564-589 (1980).

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