Histidine And Peptide Catalyze Asymmetrically Direct Aldol Reactions In Green Media

In this thesis, the direct aldol reactions between aldehydes and ketones catalyzed by histidine and dipeptide in green media have been studied in detail.In partâ… , the direct aldol reactions catalyzed by histidine in PEG-200 were studied. The results indicated that high chemical yield (96%), high diastereoselectivity (anti/syn=1/99) and good enantioselectivity (88% ee) were obtained when alicyclic ketones reacted with electron-deficient aromatic aldehydes catalyzed by histidine (30mol%) in PEG-200 or PEG-300. Thus,PEG-200 and PEG-300 are good green medium for small organo-molecular catalysis reactions.In partâ…¡, the asymmetric direct aldol reactions catalyzed by dipeptide(H-Pro-His-OH) under solvent-free condions were studied in detail. The results indicated that the dipeptide could catalyze the direct aldol reactions between electron-deficient aromatic aldehydes and ketones effectively with small load (2mol%-5mol%). The addition of small amount of water could accelerate the reactions and improve the enantioselectivity of the reactions.