Catalyst for asymmetric induction

Details Catalyst for asymmetric induction Catalyst for asymmetric induction

1994-05-11

2001-03-20

Raymond, Richard L. (Department: 1624)

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

Organic compounds

Nitriles

C544S370000

Reexamination Certificate

active

06204406

ABSTRACT:

This invention relates to a catalyst for asymmetric induction. More particularly, it relates to a catalyst comprising cyclo-[(S)-leucyl-(S)-histidyl] of the formula shown below which is referred to as cyclo-(Leu-His) hereinafter for asymmetric addition of hydrogen cyanide to aldehydes to produce the corresponding (S)-cyanohydrins.
The present inventors reported asymmetric addition of hydrogen cyanide to aldehydes in the presence of a catalyst, i.e., cyclo-[(S)-phenyl-alanyl-(S)-histidyl] [hereinafter described as cyclo-(Phe-His)] to produce the corresponding (R)-cyano-hydrins [Inoue et al, J. Chem. Soc. Chem. Commun., 229 (1981); Bull. Chem. Soc. Jpn., 59, 893 (1986)]. For example, benzaldehyde is allowed to react with hydrogen cyanide in the presence of the cyclo-(Phe-His) to obtain highly pure (R)-mandelonitrile in high yield.
After continued studies on asymmetric induction reactions catalyzed by cyclic peptides, the present inventors found that cyclo-(Leu-His) is useful as a catalyst for asymmetric addition of hydrogen cyanide to aldehydes and that the cyanohydrins obtained thereby are, to their surprise, are in (S)-configuration, while the cyanohydrins obtained by using the cyclo-(Phe-His) as a catalyst are in (R)-configuration. (S)-Cyanohydrins are useful as intermediates for production of (S)-mandelic acid, ferroelectric liquid crystals and insecticides.
The cyclic dipeptide, cyclo-(Leu-His) is a known substance [F. Schneider, Hoppe-Seyler's Z. Phys. Chem. 338, 131 (1964)], which can be prepared according to the usual peptide synthesis. For example, condensation between N-benzyloxycarbonyl-(S)-leucine and methyl ester of (S)-histidine in the presence of isobutyl chloroformate is effected in accordance with the mixed acid anhydride process to obtain methyl ester of N-benzyloxycarbonyl-(S)-leucyl-(S)-histidine and then the ester is hydrogenolyzed in the presence of palladium-carbon, followed by cyclization under reflux in methanol.
Thus obtained cyclo-(Leu-His) is useful as a catalyst for production of (S)-cyanohydrins, for example, (S)-mandelonitrile from benzaldehyde and hydrogen cyanide.
Aldehydes shown below are applicable in such asymmetric cyanation catalyzed by the present catalyst, cyclo-(Leu-His)
aromatic aldehydes such as benzaldehyde, p-methylbenzaldehyde, m-methoxybenzaldehyde, m-phenoxy-benzaldehyde, 4-fluoro-3-phenoxybenzaldehyde, 3-(4-fluorophenoxy)benzaldehyde, 3-(4-chlorophenoxy) benzaldehyde, 3-(4-bromophenoxy)benzaldehyde and 2-thiophenaldehyde
aliphatic aldehydes such as 2,2-dimethyl-propanal, 2-methylpropanal, heptanal and undecanal
alicyclic aldehydes such as cyclohexane-carboaldehyde.
The asymmetric cyanation is effected usually in the presence of from 1 to 5 mol % of the cyclo-(Leu-His) on the basis of the aldehydes. The reaction is usually carried out by allowing 2 to 5 mol of hydrogen cyanide to react with 1 mol of the aldehydes at a temperature from −20° C. to room temperature in inert solvents such as ethyl ether, isopropyl ether, toluene etc. After the reaction is over, the reaction mixture is, for example, added to dilute hydrochloric acid-methanol solution followed by removal of excess hydrogen cyanide under reduced pressure and the usual work-up to obtain the desired optically active cyanohydrins.
The present invention is explained in further detail in the following examples.


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Mori et al, “Cyclo-((S)-leucyl-(S)-histidyl) . . . Cyanide to Aldehydes”, Chemistry Letters, The Chemical Society of Japan, pp. 2119-2122, 1989.
Jun-ichi Oku et al, “Asymmetric Cyanohydrin Synthesis . . . Dipeptide”, J.C.S. Chem. Comm., pp. 229-230, 1981.
Yoshiyuki Kobayashi et al, “Asymmetric Addition of Hydrogen . . . Cyclo((S)-phenylalanyl-(S)-histidyl)”, Bull, Chem.Soc. Jpn., 59, pp. 893-895, 1986.
F. Schneider, “Reaktivitat cyclisher . . . Fermentkatalyse”, Hoppe-Seyler's Z. Phys. Chem., 338, pp. 131-144, 1964.
Aketa et al. Agric. Biol. Chem. 42(4), 895-896, 1978.*
Advances In Pesticide Science Part 2, Pergamon Press Oxford and New York, p. 174-181, 1979.

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