Stereospecificity of the addition of hydrogen cyanide to the carbonyl group of substituted 4-piperidones. Synthesis and three-dimensional structures of substituted 4-hydroxy-4-cyanopiperidines

Mixtures of stereoisomers of the corresponding 4-hydroxy-4-cyanopiperidines were synthesized by the reaction of substituted 4-piperidones with hydrogen cyanide by an exchange reaction with acetone cyanohydrin. The ratios of the stereoisomers in the resulting mixtures of stereoisomeric 4-piperidone cyanohydrins were determined by means of the 13C NMR spectra, and the three-dimensional structures were established by direct determination of the orientation of the cyano group in their molecules. A dependence of the quantitative ratios of the stereoisomeric cyanohydrins of the substituted 4-piperidones on the reaction temperature was demonstrated.