Oxynitrilase-catalyzed hydrocyanation

When Rosenthaler reported the oxynitrilase-catalyzed hydrocyanation by using almond meal in an aqueous medium in 1908 [53], this contribution not only represented one of the oldest biotransformations in organic chemistry but also the starting... 

I.3.7.I.I. (/ )-Oxynitrilase-Catalyzed Addition of Hydrocyanic Acid to Aldehydes... 

Chen, P., Han, S., Lin, G., Huang, H. and Li, Z., A study of asymmetric hydrocyanation of heteroaryl carboxaldehydes catalyzed by (i )-oxynitrilase under micro-aqueous conditions. Tetrahedron Asymm., 2001,12, 3273. 

The Sorghum (S)-oxynitrilase exclusively catalyzes the addition of hydrocyanic acid to aromatic aldehydes with high enantioselectivity, but not to aliphatic aldehydes or ketones [519, 526], In contrast, the Hevea (S)-oxynitrilase was also found to convert aliphatic and a,/ -unsaturated substrates with medium to high selectivity [509, 527]. The stereocomplementary almond (R)-oxynitrilase likewise has a very broad substrate tolerance and accepts both aromatic, aliphatic, and a,/ -unsaturated aldehydes [520, 521, 523, 528, 529] as well as methyl ketones [530] with high enantiomeric excess (Table 9). It is interesting to note that this enzyme will also tolerate sterically hindered substrates such as pivalaldehyde and suitable derivatives 164 which are effective precursors for (R)-pantolactone 165 [531],... 

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