Nitrile lyase

Nanda, S., Kato, Y. and Asano, Y., A new (i )-hydroxy-nitrile lyase from Prunus mume asymmetric synthesis of cyanohydrins. Tetrahedron, 2005, 61, 10908. 

Chapter 8 describes the application of hydroxyl nitrile lyases to the synthesis of new chiral cyanohydrins and a-hydroxy acids and includes new approaches to the transformation of difficult aldehyde and ketone substrates using substrate engineering and immobilization techniques. 

Enzymes for Carboligation - 2-Ketoacid Decarboxylases and Hydroxy nitrile Lyases 333... 

Oxynitrilase (Hydroxy Nitrile Lyase, HNL) Cyanohydrins from Aldehydes... 

Reaction studies include cyanations using hydroxy nitrile lyases, hydrolysis of amides using acylases, amidases or lipases, and even dehydration reactions of aldoximes to nitriles using aldoxime dehydratase. This reaction is quite... 

Synthesis of Chiral Cyanohydrins Using Hydroxy Nitrile Lyases (HNLs)... 

Fig. 160. The degradation of cyanogenic glycosides 1 j5-Glucosidase 2 hydroxy nitrile lyase...

Scheme 4.18 Bienzymatic reactions using hydrotg nitrile lyase.

Carbon-carbon bond formation can also be used to assemble enantiomeiically-pure secondary alcohols. Herfried Griengl of Graz University of Technology has foimd (Adv. Synth. Cat. 2007, 349,1445) that a commercial nitrile lyase effects addition of nitromethane to an aldehyde such as 24 to give the nitro alcohol 25 in high ee. Markus Kalesse of Leibniz Universitat Hannover has constructed a catalyst (Organic Lett. 2007, 9, 5637) for the enantioselective addition of the ketene silyl acetal 27 to aldehydes. Hajime Ito and Masaya Sawamura of Hokkaido University (J. Am. Chem. Soc. 2007,129, 14856) (depicted), and Dennis G. Hall of the University of Alberta (Angew. Chem. Int. Ed. 2007, 46, 5913) have reported complementary enantioselective preparations of allyl boronates such as 31. 

Chiral cyanohydrin synthesis Hydroxy nitrile lyase... 

Cabirol FL, Hanefeld U, Sheldon RA. Immobilized hydroxy-nitrile lyases for enantioselective synthesis of cyanohydrins sol-gels and cross-linked enzyme aggregates. Adv. Synth. Catal. 2006 348 1645-1654. 

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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