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Amphiphilic Hyperbranched Polyethoxysiloxane: A Self-Templating Assembled Platform to Fabricate Functionalized Mesostructured Silicas for Aqueous Enantioselective Reactions
被引:24
作者:
Zhang, Kun
[1
]
An, Juzeng
[1
]
Su, Yanchao
[1
]
Zhang, Jueyu
[1
]
Wang, Ziyun
[1
]
Cheng, Tanyu
[1
]
Liu, Guohua
[1
]
机构:
[1] Shanghai Normal Univ, Shanghai Key Lab Rare Earth Funct Mat, Minist Educ, Key Lab Resource Chem, Shanghai 200234, Peoples R China
来源:
ACS CATALYSIS
|
2016年
/
6卷
/
09期
关键词:
asymmetric catalysis;
heterogeneous catalyst;
immobilization;
mesoporous material;
silica;
ASYMMETRIC TRANSFER HYDROGENATION;
TRANSITION-METAL-COMPLEXES;
MICHAEL ADDITION;
MESOPOROUS SILICA;
AROMATIC KETONES;
ALPHA-AMINOPHOSPHONATES;
CONJUGATE ADDITION;
CHIRAL SQUARAMIDE;
WATER;
CATALYSTS;
D O I:
10.1021/acscatal.6b01315
中图分类号:
O64 [物理化学(理论化学)、化学物理学];
学科分类号:
070304 ;
081704 ;
摘要:
Fabrication of amphiphilic mesostructured silica as a heterogeneous catalyst is beneficial to facilitate an aqueous reaction due to its highly dispersed nature in water. In this work, by taking advantage of a self-templating assembled strategy, we construct two types of mesostructured silicas as heterogeneous catalysts, chiral ruthenium/diamine-functionalized and chiral cinchonine-based squaramide-functionalized heterogeneous catalysts, through the use of amphiphilic poly(ethylene glycol) monomethyl ether-modified hyper branched polyethoxysiloxane as a silica precursor. As presented in the study, the chiral ruthenium/diamine-functionalized catalyst performs an asymmetric transfer hydrogenation of acyclic alpha-trifluoromethylimines to chiral alpha-trifluoromethylamines in water, whereas the chiral squaramide-functionalized catalyst enables efficiently asymmetric Michael addition of acetylacetone to nitroalkenes in brine. Both highly catalytic performances are attributed to the combined multifunctionalities of well-defined single-site chiral active species, highly dispersed catalytic centers, and practical phase-transferred function. Furthermore, both catalysts can also be recovered easily and reused repeatedly for at least seven times without loss of catalytic activity. Such a feature makes this self-templating assembly attractive for construction of various heterogeneous catalysts.
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页码:6229 / 6235
页数:7
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