Ring Of Dipeptide Synthesis And Asymmetric Induction

Chiral cyanohydrin is one of the very important intermediates in agrochemical and pharmacy industry. Chiral cyclic dipeptide is an effective catalyst for asymmetric cyanohydrin synthesis. It summarized the development and the recently research work on chiral cyclic dipeptide as catalysis for cyanohydrination process.We have studied the process of preparation of optically active cyclic dipeptides by condensation of N-terminal protected phenylalanine and C-terminal protected histidine, Pd/C catalytic hydrogenating and cyclizing. Their structures were elucidated by m.p. IR and HNMR. The products were farther treated by fractional crystallized from different solvents .Different processes have given the product different crystal forms.Experiments were carried out by using dipeptides as catalyst for asymmetric addition of hydrogen cyanide to aldehyde. Servals catalysts were applied to asymmetric addition for being compared. Aldehyde has been coverted to cyanohydrin by using cyclo (L-Phe-L-His) as catalyst in 40.6% enantiomeric excess. A mode for the asymmetric induction of the chiral phase transfer catalyst was suggested on the basis of the results of the experiment and the relate theory.