(R)-oxynitrilase-catalysed synthesis of chiral silicon-containing aliphatic (R)-ketone-cyanohydrins

Optically active 2-trimethylsilyl-2-hydroxyl-ethylcyanide was prepared by enzymatic enantioselective transcyanation of acetyltrimethylsilane with acetone cyanohydrin in a biphasic system at 35°C and pH 5. (R)-Oxynitrilase from apple seed meal was the best among all the enzymes explored and diisopropyl ether was the most suitable organic phase. Acetyltrimethylsilane was a better substrate of the enzyme than its carbon analogue. The substrate conversion and product enantiomeric excess of 2-trimethylsilyl-2-hydroxyl-ethylcyanide were >99% and >99%, respectively.