Enzymatic Introduction of Cyanide into Imine for Constructing Optically Active Compound by (R)-Oxy-nitrilase in Almond Meal

Abstract

diastereoselective addition of HCN to aldimine derived from (S)-(-)-α-methylbenzylamine. We anticipated that the opposite ratio of two diastereomers could be obtained. However, the (R)-α-amino nitrile was obtained as a major isomer as well as the same value of diastereoisomer ratio. Almost the same values of diastereoisomer ratio was obtained in various substrates. The diastereoisomeric ratios of the products were determined by means of 1 H NMR using the signals of benzyl protons as key signals. The signals of benzyl protons CH(Me)Ph appeared in well separated quartets; the downfield (major) at δ 4.23 ppm and the upfield (miner) at δ 3.98 ppm. When the configuration of the nitrogen auxiliary was R, the (R,R)-α-amino nitriles were the resulting major products. However, when (S)-imines were applied in enzyme reaction, (S,R)-α-amino nitriles were obtained as major compounds in stead of (S,S)-α-amino nitriles. It is worth noting that the effect of the nitrogen auxiliary in imines was not observed. This result shows that the enzyme plays a major role in the