especially the effect of pores, may restrict the rotation of the
intermediate, and as a result the cis-epoxide becomes the main
product. A similar explanation was also given for the results with
Mn(salen) complexes immobilized in nanopores of Al-MCM-41
Notes and references
1
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4d
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In summary, an organic sulfonic group has, for the first time,
been used as a linkage to immobilize chiral Mn(salen) complexes
on nanopores for asymmetric epoxidation. These heterogeneous
catalysts give much higher ee values for asymmetric epoxidation of
a-methylstyrene and cis-b-methylstyrene than the homogeneous
counterparts and display high stability during the catalytic process.
cis-Epoxide as the major product was achieved for epoxidation of
cis-b-methylstyrene under heterogeneous conditions. Further
studies on the effect of surfaces and nanopores of supports are
in progress.
3
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The financial support from the National Natural Science
Foundation of China (NSFC, Grant No. 20172051 and
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20321303) is gratefully acknowledged. We would like to thank
Dr Jianliang Xiao at the University of Liverpool, UK, for helpful
discussions.
Huidong Zhang, Song Xiang and Can Li*
State Key Laboratory of Catalysis, Dalian Institute of Chemical
Physics, Chinese Academy of Sciences, Dalian, 116023, China.
E-mail: canli@dicp.ac.cn; Fax: (+86) 411-84694447;
Tel: (+86) 411-84379070
8 S. Chang, N. H. Lee and E. N. Jacobsen, J. Org. Chem., 1993, 58, 6939.
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