Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Patent
1998-12-17
2000-03-07
Killos, Paul J.
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
564302, 564304, C07C20900
Patent
active
060342781
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a novel process for the preparation of known, optically active 1-phenylethylamines, which can be used as intermediates for the synthesis of active ingredients having fungicidal or pharmacological properties.
BACKGROUND OF THE INVENTION
It is already known that (R)-1-(4-chloro-phenyl)-ethylamine can be prepared by reacting racemic 1-(4-chloro-phenyl)-ethylamine with (S)-(-)-N-phenylcarbamate lactic acid in the presence of ethanol, filtering off the resulting crystal sludge with suction and treating it with aqueous sodium hydroxide solution in the presence of methylene chloride (cf. EP-A 0 341 475). A disadvantage of this process is that there is a considerable amount of S-(-)-phenylcarbamate lactic acid in the mother liquor which results after the crystal sludge has been filtered off with suction, which can only be isolated from the liquor in a complex method.
Furthermore, it is already known that (S)-1-(4-chloro-phenyl)-ethylamine can be obtained by reducing the mother liquor which forms during the abovementioned process by distilling off ethanol, stirring the remaining residue with tert-butyl methyl ether or toluene, separating off the crystalline salt which separates out and distilling the mother liquor (cf, DE-A 4 039 447). However, this process is too expensive to be carried out on an industrial scale.
DETAILED DESCRIPTION OF THE INVENTION
It has now been found that optically active 1-phenyl-ethyl-amines of the formula ##STR1## in which X is halogen or methyl, and (S)-(-)-N-phenylcarbamate lactic acid, if ##STR2## in which X and n are as defined above ##STR3## in the presence of an aliphatic or aromatic hydrocarbon and in the presence of a lower aliphatic alcohol, the amounts of the reaction components being such that per 1 mol of racemic 1-phenyl-ethyl-amine of the formula (I), between 0.25 and 0.5 mol of (S)-(-)-N-phenylcarbamate lactic acid of the formula (II) are present,
then the lower aliphatic alcohol and, where appropriate, some of the aliphatic or aromatic hydrocarbon are distilled off at a sump temperature up to 40.degree. C., option ally under reduced pressure,
the resulting crystalline product of the formula ##STR4## in which X and n are as defined above, presence of an aliphatic or aromatic hydrocarbon, the organic phase is separated off, the aqueous phase is again stirred with an aliphatic or aromatic hydrocarbon, the organic phase is again separated off and the combined organic phases are distilled to isolate the (R)-1-phenyl-ethylamine of the formula ##STR5## in which X and n are as defined above has been separated off is reacted, in the presence of a lower aliphatic alcohol, with (S)-(-)-N-phenylcarbamate lactic acid of the formula ##STR6## where the amounts of the reaction components are such that the molar amount of (S)-(-)-N-phenylcarbamate lactic acid of the formula (II) is twice the amount of (R)-1-phenyl-ethylamine of the formula (I-R) still present in the mother liquor, then the lower aliphatic alcohol and, where appropriate, some of the aliphatic or aromatic hydrocarbon, are distilled at a sum, temperature up to 40.degree. C., optionally under reduced pressure,
the resulting crystalline product of the formula ##STR7## in which X and n are as defined above isolate the (S)-1-phenyl-ethylamine of the formula ##STR8## in which X and n are as defined above,
To denote optically active compounds, the chiral centres in the above formulae and in what follows are marked in each case by (*). The configuration of the asymmetrically substituted carbon atoms is given by the symbols (R) or (S).
It should be pointed out that it is particularly surprising that (R)-1-phenyl-ethylamines of the formula (I-R) can be prepared by the process according to the invention in extremely high yield and excellent optical purity. On the basis of the known prior art, it could not have been expected that the respective salt of (R)-1-phenyl-ethylamine and (S)-(-)-N-phenylcarbamate lactic acid would form preferentially from the hydrocarbon p
REFERENCES:
patent: 4874420 (1989-10-01), Wroblowsky et al.
patent: 4988734 (1991-01-01), Kraatz et al.
patent: 5144077 (1992-09-01), Jansen et al.
patent: 5183939 (1993-02-01), Jansen et al.
E. Brown et al, Tetrahedron Letters, vol. 26, No. 37, (month unavailable) 1985, pp. 4451-4452.
Kraatz Udo
Littmann Martin
Mannheims Christoph
Merz Walter
Bayer Aktiengesellschaft
Gil Joseph C.
Killos Paul J.
Marmo Carol
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