Chiral Proline Derivative Anchored on Mesoporous SBA-15 Silica：Synthesis and Application
Date Issued
2006
Date
2006
Author(s)
Hsiao, Li-Hsiu
DOI
zh-TW
Abstract
Mesoporous SBA-15 silica materials were functionalized with chloropropyl group either through co-condensation of tetraethyl orthosilicate (TEOS) and (3-chloropropyl)-trimethoxysilane (CPTMS) in the presence of triblock copolymer P123 as structure directing agent under acidic condition or by grafting calcined SBA-15 silica with CPTMS. The chloropropyl groups were then converted to chiral proline derivative (α,α-Diphenyl-L-prolinol) through nucleophilic substitution with proline derivative. The resultant materials were characterized by various techniques including X-ray powder diffraction, solid state NMR, elemental analysis to verify the structure and chemical composition. These functionalized materials were applied to asymmetric diethylzinc addition to benzaldehyde as chiral selective catalysts.
The enantioselectivity of 1-phenyl-propanol was found to be markedly dependent on the amount and the distribution of the prolinol groups inside the mesopores. High enantiometric excess 66% e.e. was achieved when 15%Cl-tolu-cata was used as the chiral catalyst. In addition, better enantiometric excess of 75% was obtained if n-BuLi was also added in the reaction. The reaction rate was also influenced by the hydrophobic environment around the active sites and the reaction rate increased when the walls of mesoporous silica were functionalized with methyl groups. Finally, the enantioselectivity and reaction rate were found to retain when the used catalysts were reused.
Subjects
介孔SBA-15
Proline衍生物
掌性
mesoporous SBA-15
proline derivative
chiral
Type
thesis
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