Hydroxynitrile lyase stereoselective synthesis

The hydroxynitrile lyase (HNL)-catalyzed addition of HCN to aldehydes is the most important synthesis of non-racemic cyanohydrins. Since now not only (f )-PaHNL from almonds is available in unlimited amounts, but the recombinant (S)-HNLs from cassava (MeHNL) and rubber tree (HbHNL) are also available in giga units, the large-scale productions of non-racemic cyanohydrins have become possible. The synthetic potential of chiral cyanohydrins for the stereoselective preparation of biologically active compounds has been developed during the last 15 years. 

Roberge, C., Fleitz, F., Pollard, D. and Devine, P., Synthesis of optically active cyanohydrins from aromatic ketones evidence of an increased substrate range and inverted stereoselectivity for the hydroxynitrile lyase from Linum usitatissimum. Tetrahedron Asymm., 2007,18, 208. 

Effenherger, F., Hydroxynitrile lyases in stereoselective synthesis. In Stereoselective Biocatalysis, Patel, R.N. (ed.). Dekker New York, 2000 pp. 321-342. 

The stereoselectivity of the hydroxynitrile lyase (HNL) catalysed cyanohydrin formation of monosubstituted cyclic ketones is of general interest for the synthesis of biologically active compounds. In the course of a systematic investigation of the stereoselectivity of HNL-catalysed addition of HCN to a variety of monosubstituted cyclopentanones, Kobler and Effenberger observed a DKR for the addition of HCN to alkyl 2-oxocyclopentanecarboxylates... 

---