Process for the preparation of optically active methionine amide

Details Process for the preparation of optically active methionine amide Process for the preparation of optically active methionine amide

1993-07-09

1995-11-21

Kumar, Shailendra

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

Organic compounds

Amino nitrogen containing

564192, 564193, 564197, C07C23305, C07C23706

Patent

active

054689015

ABSTRACT:
The invention relates to a process for preparing optically active methionine amide in high ee purities in which a mixture of D- and L-methionine amide or the Schiff bases thereof is at least partly converted, optionally in the presence of 0.5-4 equivalents of an aldehyde, relative to the amount of methionine amide, and water, in the presence of an organic solvent, using less than 1.2 equivalents of L- or D-mandelic acid, respectively, relative to the amount of D- or L-methionine amide, respectively, or the Schiff bases thereof, present in the mixture of D- and L-methionine amide or the Schiff bases thereof, into a salt of methionine amide and mandelic acid, a portion consisting substantially of one of the diastereoisomers of the salt is separated from the reaction mixture obtained, and the salt is converted into the optically active methionine. A high degree of optical purity is obtained. This process can be advantageously combined with a preparation of D,L-methionine amide from D,L-methionine nitrile by returning the residual methionine amide obtained after separation of the diastereomeric salt and recovery of the mandelic acid to the preparation of D,L-methionine amide where racemization of the recycled methionine amide takes place in situ. A high overall efficiency can thus obtained in spite of a relatively low efficiency of conversion into the diastereoisomeric salt, relative to the amount of D- and L-methionine amide, or the Schiff bases thereof, used.

REFERENCES:
patent: 4847412 (1989-07-01), Boesten et al.
Pope, W. J. et al., "Externally Compensated Tetrahydroguinaldine (Tetrahydro-2-methylquinoline) and its Optically Active components., ", Journal Chem. Soc. 2199 (1910).
Jacques, Jean et al., "Crystallization-Induced Asymmetric Transformations, " Enantiomers, Racemates, and Resolutions, pp. 369-377 (1981).

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