The Development of Enantioselective Cyanohydrin Synthesis by Artificial Enzyme.

研究了环二肽催化氰化氢加成醛对映选择性氰丙烷的合成。以苯甲醛为底物，利用由苯丙氨酸和s -组氨酸两个氨基酸残基组成的环状二肽环-（苯丙酰- s -组氨酸），得到了相应的氰醇，其对映体过量（ee）达97%，化学产率达97%。而以环- （s -亮基- s -组氨酸）为催化剂生成s -氰醇时，其立体反应倾向发生了逆转。由此，建立了通过选择环二肽中的氨基酸残基合成两种对映体的氰醇方法。此外，用环- （S-苯丙基-S-组氨酸）和环- （S-亮基-S-组氨酸）对α、β -不饱和醛进行了氢化反应，分别得到了相应的R和S氰醇。

Enantioselective cyanohydrin synthesis catalyzed by cyclic dipeptide by the addition of hydrogen cyanide to aldehydes is carried out. When benzaldehyde was employed as a substrate, optically active mandelonitrile, the corresponding cyanohydrin, was obtained with the enantiomeric excess (ee) of 97%and 97% chemical yield by using the cyclic dipeptide, cyclo- (Phenylalanyl-S-hisidyl) composed of two amino acid residues, Sphenylalanine and S-histidine. The stereochemical outcome of the mandelonitrile was found to be R. On the other hand, the inversion of the stereochemical preference was observed when cyclo- (S-leucyl-S-histidyl) is used as a catalyst to give S-cyanohydrins. Thus, the methodology for the cyanohydrin syntheses of both enantiomers by selecting the amino acid residue in the cyclic dipeptide is established. In addition, hydrocyanation of alpha, beta-unsaturated aldehyde by using cyclo- (S-phenyalanyl-S-histidyl) and cyclo- (S-leucyl-S-histidyl) is carried out to give the corresponding R and S cyanohydrins respectively.