Engineering Chiral Polyoxometalate Hybrid Metal鈥揙rganic Frameworks for Asymmetric Dihydroxylation of Olefins

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• 作者：Qiuxia Han ; Cheng He ; Min Zhao ; Bo Qi ; Jingyang Niu ; Chunying Duan
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：July 17, 2013
• 年：2013
• 卷：135
• 期：28
• 页码：10186-10189
• 全文大小：329K
• 年卷期：v.135,no.28(July 17, 2013)
• ISSN：1520-5126

文摘

Chiral metal鈥搊rganic frameworks (MOFs) with porous and tunable natures have made them feasible for performing a variety of chemical reactions as heterogeneous asymmetric catalysts. By incorporating the oxidation catalyst [BW₁₂O₄₀]^{5鈥?/sup> and the chiral group, l- or d-pyrrolidin-2-ylimidazole (PYI), into one single framework, the two enantiomorphs Ni-PYI1 and Ni-PYI2 were obtained via self-assembly, respectively. The channels of Ni-PYIs were enlarged through a guest exchange reaction to remove the cationic chiral templates and were well modulated with hydrophilic/hydrophobic properties to allow molecules of both H₂O₂ and olefin ingress and egress. The coexistence of both the chiral directors and the oxidants within a confined space provided a special environment for the formation of reaction intermediates in a stereoselective fashion with high selectivity. The resulting MOF acted as an amphipathic catalyst to prompt the asymmetric dihydroxylation of aryl olefins with excellent stereoselectivity.}