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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.

1. Wajant, H., Effenberger, F., Biol. Chem. 1996, 377, 611-617.
2. Effenberger, F., Angew. Chem. Int. Ed. Engl. 1994, 33, 1555-1564.
3. Jackson, W.R., Aust. J. Chem. 1990, 43, 2045-2062.
4. Kruse, C.G. in Chirality in Industry (eds. Collins, A.N.; Sheldrake, G.N.; Crosby, J.), Wiley, New York, 1992, pp. 279-299

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* Invited lecture presented at the International Conference on Bioversity and Bioresources: Conservation and Utilization, 23-37 November 1997, Phuket, Thailand.