Synthesis Of Chiral Ferrocenyl Aziridino Ring Ligands And Their Application In The Asymmetric Catalysis

In this thesis, a new ferrocenyl phosphine-containing compound and a new couple of ferrocenyl aziridino alcohol diastereomers as chiral ligands were synthesized from readily available natural L-serine. The asymmetric ethylation of benzaldehyde O-tosyl oxime and benzaldehyde was investigated in the presence of a mount of chiral ligand. Asymmetric addition of dimethylzinc to aldhydes catalysed by (S)-(1-ferrocenylaziridin-2-yl)diphenylmethanol was also evaluated.1. The synthesis of new chiral ferrocenyl phosphine-containing ligand and its application in the asymmetric addition of diethylzinc to benzaldehyde O-tosyl oxime.Chiral ligands 9 was prepared from easily available L-serine by all eight steps including the esterification, protection, cyclization, reduction, sulfonylation, deprotection and so on. The novel compounds 8 and 9 were characterized by ¹H NMR, ¹³C NMR, IR and MS. The specific rotation of compounds 3-9 were recorded. The efficiencies of the chiral ligand 9 was examined for the asymmetric addition of diethylzinc to benzaldehyde O-tosyl oxime in the presence of Cu(OTf)₂. The preliminary result showed that the chiral ligand 9 was an effective catalyst for the asymmetric addition of diethylzinc to benzaldehyde O-tosyl oxime affording the corresponding addition products with yield of up to 85.5%, but low enantioselectivity (20.8% ee).2. The synthesis of chiral ferrocenyl aziridino alcohol ligands possessing two central chirality and their application in the asymmetric addition of diethylzinc to benzyl aldehyde.(1) Starting from L-serine, chiral ligands 27a and 27b were prepared by esterification, condensation, reductive alkalation, cyclization, reduction, oxidation, then treatment with PhMgX. The two novel compounds were characterized by ¹H NMR, ¹³C NMR, IR and MS.(2) The chiral ligands 27a and 27b were used as catalyst to promote the asymmetric addition of diethylzinc to benzaldehyde affording the corresponding addition products with enantioselectivity of 45.3% ee and 5% ee respectively. The results showed that the two central chiralty matching each other was the key to have a good ee value. 27b which is the diasteomer of 27a afforded enantioselectivity of 5% ee only, suggesting that the two central chiralty are "mismatched". 3. The application of (S)-(1-ferrocenylaziridin-2-yl)diphenylmethanol in the asymmetric addition of dimethylzinc to aldehydes.(1) Starting from the compound 24, chiral ligand L4 was prepared.(2) The effect of chiral ligand L4 on the reactivity and enantioselectivity of reaction was investigated in the asymmetric addition of diethylzinc to arylaldehydes. The result suggested that L4 can catalyse the asymmetric addition of dimethylzinc to arylaldehydes effectively. When the substrate is 4-CH3PhCHO, it afforded the corresponding addition products in up to 95.0% ee with high to excellent yield of 99.8%.