Synthesis of novel chiral phosphinite, phosphite and phosphinous amide ligands and their applications on the asymmetric catalytic reactions

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Synthesis of novel chiral phosphinite, phosphite and phosphinous amide ligands and their applications on the asymmetric catalytic reactions

 

Author: Guo, Rongwei
Title: Synthesis of novel chiral phosphinite, phosphite and phosphinous amide ligands and their applications on the asymmetric catalytic reactions
Degree: Ph.D.
Year: 2002
Subject: Hong Kong Polytechnic University -- Dissertations
Phosphorus compounds -- Analysis
Asymmetric synthesis
Chirality
Stereochemistry
Department: Dept. of Applied Biology and Chemical Technology
Pages: xvii, 279 p. : ill. ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b1663548
URI: http://theses.lib.polyu.edu.hk/handle/200/850
Abstract: In this study, we have synthesized a series of novel chiral ligands-phosphinite, phosphite and phosphinous amide ligands from commercial chiral building blocks conveniently. Their transition-metal complexes have been found to be effective catalysts in the asymmetric hydrogenation or hydroformylation of olefins. Some ligands were found to be effective in the asymmetric conjugated-addition reactions. The rhodium complex containing phosphinous ligands 89 (Xyl-BDPAB) which derived from 2,2'-diamino-1,1'-binaphthyl and bis(3,5-dimethylphenyl)phosphine chloride gave excellent enantioselectivity in the asymmetric hydrogenation of dehydroamino acids and esters or in the asymmetric hydrogenation of enamides. The best e.e. values were up to 99%. In addition to the high enantioselectivity, the catalyst also exhibited excellent catalytic activity. The hydrogenation of model substrates N-( I-phenylethenyl)acetamide or methyl acetamidocinnamate proceeded smoothly in the appropriate solvent at ambient temperature and under 50psi H2 for 10 min. leading the hydrogenated products with quantitative yield and 98% ee. The effects of the backbones and the substituents on the phosphors atoms of the chiral ligands in catalyzed hydrogenation of the prochiral olefins were extensively investigated, and the results strongly supported our cognition for the designing efficient chiral ligands. Copper complex of N-containing phosphite ligand 101 has been found to be effective for the asymmetric conjugated addition of diethylzinc to the cyclohexyl-l-one. The best ee's was obtained in 92% ee and in quantitative yield with conjugated addition of diethylzinc to the cyclohexyl-1-one. The variation N-containing phosphite ligands were also investigated in the asymmetric hydroformylation of styrene. They also gave high activities and regioselectivities with moderate to good enantioselectivities. The molar ratio of branch to linear hydro-formylation products was up to 97/3 and the ee's was up to 49%. A series of phosphinite ligands that derived from binaphthol and D-mannitol were also investigated in the asymmetric hydrogenation of dehydroamino acids and derivatives. They also gave high activities and good to excellent enantioselectivities. In order to get the hints into the relationship between enantioselectivity and the structure of the chiral ligands, several single crystal structures of phosphinite ligands and phosphinous amide ligands were determined and helpful information was obtained.

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