77941-92-5Relevant academic research and scientific papers
Efficient Catalytic Performance for Acylation-Nazarov Cyclization Based on an Unusual Postsynthetic Oxidization Strategy in a Fe(II)-MOF
Shao, Zhichao,Liu, Mengjia,Dang, Jian,Huang, Chao,Xu, Wenjuan,Wu, Jie,Hou, Hongwei
, p. 10224 - 10231 (2018)
A rare example of SC-SC triggered by Cu2+ heterogeneous oxidation was demonstrated in a Fe(II)-based MOF {[FeII3(L)2(H2O)6]·3H2O}n (1), which occurred a slow conversion into an oxidized MOF 2 ({[FeIII3(L)2(H2O)6]·3(OH)}n) with retention of single crystallinity. The FeII → FeIII progress of the reaction oxidation was proved by single crystal XRD, PXRD, XPS, 57Fe M?ssbauer spectroscopy, and UV-vis. We used 1 and 2 as catalysts to catalyze the tandem Nazarov cyclization, and the results show that acylation products were only harvested when 1 was a catalyst, while the oxidized transformer 2 lead mainly to the formation of cyclization products under identical conditions. Through the test of different substrates, 2 can be a good heterogeneous catalyst candidate for the formation of cyclopentenone[b] benzenes. This work provides a new way to design efficient and hard-synthesized heterogeneous catalyst materials.
Co-Cluster-Based Metal–Organic Frameworks as Selective Catalysts for Benzene Tandem Acylation–Nazarov Cyclization to Benzocyclopentanone
Liu, Mengjia,Gao, Kuan,Fan, Yanru,Guo, Xiaoqing,Wu, Jie,Meng, Xiangru,Hou, Hongwei
supporting information, p. 1416 - 1424 (2018/02/06)
One-step selective benzene acylation–Nazarov cyclization is an attractive, yet challenging method for the synthesis of the benzocyclopentanone skeleton, which is key intermediate of many natural products. Herein, two metal-cluster-based metal–organic frameworks (MCOFs) {(H3O)2[Co4(pbcd)2(μ3-OH)2]?CH3CH2OH?4 H2O}n (1; pbcd=9,9′-(propan-1,3-diyl)bis(9H-carbazole-3,6-dicarboxylic acid) and {[Co5.25(mcd)2(HCO2)(μ2-O)0.5(μ3-OH)0.5(H2O)4]?6 H2O?5 DMF}n (2; mcd=9,9′-methylenebis(9H-carbazole-3,6-dicarboxylic acid) were developed to catalyze a tandem Nazarov cyclization reaction of 1,3-dimethoxybenzene with α,β-unsaturated carboxylic acids for the synthesis of cyclopentenone[b]benzenes. MCOFs 1 and 2, which were constructed from tetranuclear CoII cluster [Co4(μ3-OH)2] and hexanuclear CoII cluster [Co6(HCO2)(μ2-O)(μ3-OH)], respectively, exhibit high catalytic activity arising not only from their suitable channel size and accessible catalytic sites, but also because of their high density of Lewis acidic sites within the frameworks and the synergic activity among CoII ions. In contrast, {[Co2(pbcd)(bpe)]?2 H2O?2 DMF}n (3; bpe=1,2-bis(pyridin-4-yl)ethane) containing binuclear CoII and having large pore windows is a highly selective catalyst for obtaining exclusively the acylation products. Easy product separation, simple reaction procedures, and catalyst recycling make the catalyst system attractive. This work highlights the synergistic effect among ions of MCOFs in interacting with substrates in a sequential or cooperative manner to achieve tandem catalysis.
