Catalytic Asymmetric Benzaldehyde Cyanohydrin Synthesis with Synthetic Optically Active Polymer. III. N-Substituted Poly-(s)-isobutylethylenimine

Asymmetric syntheses of benzaldehyde cyanohydrin in the presence of polymers of N-methyl-,N-ethyl- and N-benzyl-(s)-2-isobutylethylenimine as catalysts have been studied. The selectivity of these polymers was poor (optical yield of (−)-isomer obtained; 0–1%) compared with that of a non-N-substituted polymer (20%). It seems that the large difference in the optical yield can be ascribed to their conformation. As to the polymer being capable of promoting the reaction asymmetrically, it is assumed that the isobutyl group and a helical form are the responsible factors. On the basis of these findings, a model for the addition step has been suggested in order to explain the observed result.