Hydrocyanation of 3-Pyridinecarboxyaldehyde

The 3-pyridinecarboxyaldehyde 58 is highly water soluble, and so the spontaneous cyanide addition to give racemic cyanohydrin cannot be suppressed unless the aqueous pH is lowered below 3.5, which is not tolerated by the enzymes. The only available option is to operate in a 100% organic solvent system. This was recently made possible by the availability of the cross linked enzyme aggregate particles (CLEAs), which can tolerate organic solvents [64]. The individual precipitated protein molecules are chemically bonded to one another through the formation 

186 7 Industrial-Scale Applications of Enzymes in Non-Aqueous Solvents OH 

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Recently the Merck research laboratories demonstrated the synthesis of both (R) and (S)-cyanohydrins (59, 60) with >93% through hydrocyanation of 3-pyridinecarboxyaldehyde (58) in >65% yield using dichloromethane (Scheme 7.23)... 

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