Synthesis of novel cyano-cyclitols and their stereoselective biotransformation catalyzed by Rhodococcus erythropolis A4

A variety of novel cyano-cyclitols possessing complex stereochemistry have been synthesized. These compounds were subjected to the biocatalyzed hydrolysis of their nitrile groups. The bacterial strain Rhodococcus erythropolis A4, expressing a nitrile hydratase/amidase bienzymatic system, was able to recognize (1R,2S,3S,4R)/(1S,2R,3R,4S)-1-cyano-2,3,4-trihydroxy-cyclohex-5-ene and trans-3-cyanocyclohexa- 3,5-diene-1,2-diol, and to catalyze their transformations into the corresponding amides and acids. The kinetic and stereochemical trends of these biotransformations, a rare example of the enantiorecognition of a rigid bulky aliphatic substrate, are discussed.