Studies On The Catalytic Asymmetric Methylation And Alkynylation Of Aldehydes

In this thesis, an enantiopure L-N-ferrocenylmethyl azetidin-2-yl(diphenyl)-methanol 10 was synthesized from readily available natural L-methionine. The compound 10 as the chiral ligand was applicated in the catalytic asymmetric addition of dimethylzinc and alkynylzinc to aldehydes.1. The synthesis of chiral compound 10 and its crystal structureChiral ligand 10 was prepared from easily available L-methionine 1 by methylation, hydrolization, bromization, esterification, condensation, reduction, cyclization, and then treating with PhMgX. The chiral compound 10 was characterized by ¹H NMR, ¹³C NMR, IR and MS. The melting point and specific rotation of 10 were recorded. The ee value of 10 was determined by HPLC analysis and was up to 99.9%. The crystal structure of 10 containing two HOAc molecules was obtained in the presence of the mixture of ethyl acetate, hexane and HOAc, and confirmed further by X-ray diffraction. 2. The application of chiral ligand 10 in the catalytic asymmetric addition of dimethylzinc to aldehydesChiral ligand 10 catalyzed asymmetric methylation of aldehydes with dimethylzinc was investigated. In the presence of 5 mol% chiral ligand 10, asymmetric additions of dimethylzinc to aldehydes afford the corresponding addition products in up to 94.1% enantiomeric excess with up to 97.5% yield.3. The application of chiral ferrocenyl azetidino alcohol ligand in the catalytic asymmetric addition of alkynylzinc to arylaldehydesChiral ligand 10 catalyzed asymmetric alkynylation of arylaldehydes with alkynylzinc was investigated. In the presence of 10 mol% chiral ligand 10 and 10 mol% DiMPEG, the enantioselective alkynylation of arylaldehyde afforded addition products with enantioselectivity up to 84.3% ee and in yield up to 90.6%.