Synthesis Of New Chiral Ferrocenyl Azetidino Alcohol Ligands And Their Application In The Asymmetric Catalysis

In this thesis, ten novel enantiopure ferrocenyl azetidino alcohols as chiral ligands were designed and synthesized from readily available natural L-amino acids. The systematic studies on these chirality ligands were carried out for the application in the catalytic asymmetric addition of diethylzinc as well as arylboronic acids to arylaldehydes. A 'one-pot' procedure for the synthesis of N-ferrocenylmethylazetidine-2-carboxylic ester from L-bromic homoserine ester was developed. Chiral ferrocenyl N,P-containing ligands were first applied in the catalytic asymmetric conjugated addition of diethylzinc to chalcones.1. The synthesis of chiral ferrocenyl azetidino alcohol ligands and their application in the catalytic asymmetric addition of diethylzinc to aldehydesChiral ligands 9a-j were prepared from easily available L-methionine 1 by methylation, hydrolization, bromization, esterification, condensation, reduction, cyclization, and then treated with RMgX. 11 kinds of novel chiral compounds were characterized by ¹HNMR, ¹³CNMR, IR and HRMS. The specific rotation of these compounds were recorded. The ee values of 8a and 9i was determined by HPLC analysis and was more than 99%. The chiral ligands of 9a-j were used as catalysts to promote the asymmetric addition of diethylzinc to arylaldehydes affording the corresponding 1-aryl-1-propanol in up to 99.8 % enantiomeric excess with up to 100% yield. The effect of the ligand structures on the enantioselectivity of reaction was then examined. It was further demonstrated that the replacement of the phenyl group on the nitrogen atom of aziridine-based skeleton with a ferrocenyl unit led to a dramatically improvement in the enantioselectivity when used as the catalyst in the addition of diethylzinc to benzaldehyde. A simple three-step, one-pot protocol for the efficient prepatation of three chiral enantiopure methyl N-alkyl-azetidine-2-carboxylates ligands 8 was developed involving condensation, reduction and cyclization. 2. The application of chiral ferrocenyl azetidino alcohol ligands in the catalytic asymmetric addition of arylboronic acids to aldehydesChiral N-ferrocenylmeth-yl azetidin-2-yl(diphenyl)methanol 9i catalyzed asymmetric aryl transfer reactions to aldehydes with boronic acids as aryl source were investigated. In the presence of a catalytic amount (10% mol) of the chiral N-ferrocenylmethyl azetidin-2-yl(diphenyl)methanols 9i, the enantioselective arylation of arylaldehyde afforded addition products with enantioselectivity of up to 95.7% ee and in yield of up to 99%. 3. The synthesis of new chiral ferrocenyl N,P-containing ligands and their application in the Cu catalysted asymmetric conjugated addition of diethylzinc to chalconesApplication of chiral ferrocenyl N,P-containing ligands with planar chirality and centre chirality in the Cu catalyzed asymmetric conjugated addition of diethylzinc to chalcones were studied. In the presence of a catalytic amount of the chiral ligands L₂₇ and L₂₈, the enantioselective ethylation of chalcones 17 afforded addition products with enantioselectivity of up to 92% ee and in yield of up to 95%.