Hydroxynitrile Manihot esculenta

Chiral cyanohydrins are versatile intermediates in the synthesis of a-hydroxy acids, /3-amino alcohols, amino nitriles, a-hydroxy ketones and aziridines. For the synthesis of enantiopure cyanohydrins, the use of hydroxynitrile lyases is currently the most effective approach.Application of an organic-solvent-free system allows thermodynamically hindered substrates to be converted with moderate to excellent yields. With the use of the highly selective hydroxynitrile lyase from Manihot esculenta, the syntheses of several acetophenone cyanohydrins with excellent enantioselectivities were developed (Figure 8.2). (5)-Acetophenone cyanohydrin was synthesized on a preparative scale. ... 

J. Hughes, Z. Keresztessy, K. Brown, S. Suhandono, M. A. Hughes, Genomic organization and structure of % hydroxynitrile lyase in cassava (Manihot esculenta Grantz). Arch. Biochem. Biophys. 1998, 356,107-115. 

Hnl hydroxynitrile lyase Pa Prunus amygdalus Hb Hevea hrasiliensis Sb Sorghum hicolor Me Manihot esculenta. 

F. Effenberger, and K. Pfizenmaier, Enantioselective synthesis of aliphatic (S)-cyanohydrins in organic solvents using hydroxynitrile lyase from Manihot esculenta, Ann. N. Y. Acad. Sci. 1996, 799, 771-776. 

Chmura, A., van der Kraan, G.M., Kielar, F., van Langen, L.M., van Rantwijk, F. and Sheldon, R.A. (2006) Cross-linked aggregates of the hydroxynitrile lyase from Manihot esculenta highly active and robust biocatalysts. Adv. Synth. Catcd., 348, 1655. 

Hughes, J., de Carvalho, F.J.P and Hughes, M.A. (1994) Purification, characterization and cloning of a-hydroxynitrile lyase from cassava (Manihot esculenta Crantz). Ardz. 

Change of product configuration owing to a priority replacement according CIP rules Abbreviations HNL, hydroxynitrile lyase P. a., Prunus amygdalus S. b., Sorghum bicolor, H. b., Hevea brasi-liensis M. e., Manihot esculenta I. u., Linum usitatissimum. 

Figure 11.14 Synthesis of (S)-2-hydroxycarboxylic amides using a one-pot cascade of (S)-hydroxynitrile lyase from Manihot esculenta (MeHnL) and nitrile hydratase from Nitriliruptor alkaliphilus (NHase). R = vinyl, ethyl, propyl, isopropyl, butyl.

H. Biihler, F. Effenberger, S. Forster, J. Roos, H. Wajant, Substrate specificity of mutants of the hydroxynitrile lyase from Manihot esculenta, Chembiochem 4 (2003) 211-216. 

S-Hydroxynitrile Lyases from Manihot esculenta and from Hevea brasiliensis... 

On the other hand, various ( l-cyanohydrins have been prepared using (5)-hydroxy-nitrile lyases from plants (Fig. 34). The (5)-cyanohydrins can be further converted to a-hydroxy acids by acid hydrolysis without racemization [107]. A recent example is the hydroxynitrile lyase from Manihot esculenta, which was cloned in E. coli and used as chiral catalyst for the synthesis of a broad range of optically active a-hydroxynitriles including keto-(5)-cyanohydrins using diisopropyl ether as organic solvent and HCN as cyanide source [112]. Compared to the enzymes from leaves, the overexpressed enzyme in E. coli showed higher enantioselectivity. 

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