(R)-(+)-Binol-functionalized mesoporous organosilica as a highly efficient pre-chiral catalyst for asymmetric catalysis.
(R)-(+)-Binol-functionalized mesoporous organosilica as a highly efficient pre-chiral catalyst for asymmetric catalysis.
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DOI：
10.1002/asia.200900737
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发表时间：
2010-05
期刊：
影响因子：
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通讯作者：
Xiao Liu;Peiyuan Wang;Yan Yang;Peng Wang;Qihua Yang
中科院分区：
文献类型：
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作者：
Xiao Liu;Peiyuan Wang;Yan Yang;Peng Wang;Qihua Yang
(R)-(以三嵌段共聚物P123为模板剂，（R）-2，2 '-二甲氧基甲基氧基-6，6'-二（1-丙基三甲氧基硅基）-1，1 '-联萘（BSBinol）与1，2-二（三甲氧基硅基）乙烷（BTME）和四甲氧基硅烷（TMOS）在酸性溶液中共缩合，成功合成了具有不同骨架组成的（+）-二醇功能化手性周期介孔有机硅（PMO）。BTME和BSBinol的混合物可以在酸性介质中得到高度有序的介孔结构，而使用TMOS和BSBinol的混合物合成的介孔材料只能在弱酸性缓冲溶液中得到。所有材料都是高效的催化剂（与Ti配位），用于二乙基锌与醛的不对称加成反应。该催化剂的对映体选择性高达90%，转换频率（TOF）为104 h（-1），高于以甲苯为溶剂的均相（R）-（+）-Binol催化剂（83% ee，TOF为96 h（-1））。这项工作证明了刚性孔壁在增加手性PMO的对映选择性方面的积极作用。
(R)-(+)-Binol-functionalized chiral periodic mesoporous organosilicas (PMOs) with different framework compositions were successfully synthesized by cocondensation of (R)-2,2'-di(methoxymethyl)oxy-6,6'-di(1-propyltrimethoxysilyl)-1,1'-binaphthyl (BSBinol) with 1,2-bis(trimethoxysilyl)ethane (BTME) and tetramethoxysilane (TMOS) using triblock copolymer P123 as a template in acidic solution. The mixture of BTME and BSBinol can result in a highly ordered mesostructure in an acidic medium but the mesoporous materials synthesized using a mixture of TMOS and BSBinol can only be obtained in a weak acidic buffer solution. All the materials are efficient catalysts (coordinated with Ti) for asymmetric addition of diethylzinc to aldehydes. The chiral PMO with ethane and (R)-(+)-Binol in the framework exhibits an enantioselectivity as high as 90% with a turnover frequency (TOF) of 104 h(-1), which is even higher than the homogeneous (R)-(+)-Binol catalyst (83% ee with TOF of 96 h(-1)) using toluene as solvent under similar conditions. This work demonstrates the positive effect of the rigid pore wall in increasing the enantioselectivity of the chiral PMOs.