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Pure Appl. Chem., Vol. 70, No. 11,
pp. 2136, 1998
Hydroxynitrile lyases, interesting biocatalysts
in stereoselective organic syntheses*
Franz Effenberger
Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
E-mail: [email protected]
Abstract: The release of HCN (cyanogenesis) is widely distributed
in higher plants (Spermaphyta), including important food plants
like cassava and sorghum. During cyanogenesis first cyanohydrin-O-glucosides
are cleaved into sugars and the corresponding cyanohydrins. In a second
step, by action of a hydroxynitrile lyase (HNL), the cyanohydrins are
cleaved to give HCN and aldehydes or ketones, respectively.1
HNLs not only catalyse the cleavage of cyanohydrins, but also the enantioselective
addition of HCN to aldehydes or ketones yielding optically active cyanohydrins
((R)-1, (S)-1).1,2
The isolation characterization and applications in syntheses of the
hydroxynitrile lyases PaNHL from Prunus amygdalus (bitter almond),
SbNHL from Sorghum bicolor and MeNHL from Manihot esculanta
(cassava) are discussed.1
Follow up reactions of the optically active cyanohydrins can be conducted
with retention of the chiral center, and further stereogenic centers
can be introduced diastereoselctively.1-4 Stereoselective
syntheses of optically active a -hydroxy acids, 2-amino alcohols
and tetronic acids, starting from chiral cyanohydrins, are described.
O-Sulfonylated optically active cyanohydrins react easily with O, N
and S-nucleophiles under complete inversion of configuration leading
to interesting compounds such as 1,2-diamines, 2-mercapto acids, 2-amino
acids etc.
-
Wajant, H., Effenberger, F., Biol.
Chem. 1996, 377, 611-617.
-
Effenberger, F., Angew. Chem.
Int. Ed. Engl. 1994, 33, 1555-1564.
-
Jackson, W.R., Aust. J. Chem.
1990, 43, 2045-2062.
-
Kruse, C.G. in Chirality in Industry
(eds. Collins, A.N.; Sheldrake, G.N.; Crosby, J.), Wiley, New York,
1992, pp. 279-299
* Invited lecture presented at the
International Conference on Bioversity and Bioresources: Conservation
and Utilization, 23-37 November 1997, Phuket, Thailand.
Page last modified 14 April 1999.
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