91851-16-0Relevant articles and documents
Strongly Lewis Acidic Metal-Organic Frameworks for Continuous Flow Catalysis
Ji, Pengfei,Feng, Xuanyu,Oliveres, Pau,Li, Zhe,Murakami, Akiko,Wang, Cheng,Lin, Wenbin
, p. 14878 - 14888 (2019)
The synthesis of highly acidic metal-organic frameworks (MOFs) has attracted significant research interest in recent years. We report here the design of a strongly Lewis acidic MOF, ZrOTf-BTC, through two-step transformation of MOF-808 (Zr-BTC) secondary building units (SBUs). Zr-BTC was first treated with 1 M hydrochloric acid solution to afford ZrOH-BTC by replacing each bridging formate group with a pair of hydroxide and water groups. The resultant ZrOH-BTC was further treated with trimethylsilyl triflate (Me3SiOTf) to afford ZrOTf-BTC by taking advantage of the oxophilicity of the Me3Si group. Electron paramagnetic resonance spectra of Zr-bound superoxide and fluorescence spectra of Zr-bound N-methylacridone provided a quantitative measurement of Lewis acidity of ZrOTf-BTC with an energy splitting (?E) of 0.99 eV between the ?x? and ?y? orbitals, which is competitive to the homogeneous benchmark Sc(OTf)3. ZrOTf-BTC was shown to be a highly active solid Lewis acid catalyst for a broad range of important organic transformations under mild conditions, including Diels-Alder reaction, epoxide ring-opening reaction, Friedel-Crafts acylation, and alkene hydroalkoxylation reaction. The MOF catalyst outperformed Sc(OTf)3 in terms of both catalytic activity and catalyst lifetime. Moreover, we developed a ZrOTf-BTC?SiO2 composite as an efficient solid Lewis acid catalyst for continuous flow catalysis. The Zr centers in ZrOTf-BTC?SiO2 feature identical coordination environment to ZrOTf-BTC based on spectroscopic evidence. ZrOTf-BTC?SiO2 displayed exceptionally high turnover numbers (TONs) of 1700 for Diels-Alder reaction, 2700 for epoxide ring-opening reaction, and 326 for Friedel-Crafts acylation under flow conditions. We have thus created strongly Lewis acidic sites in MOFs via triflation and constructed the MOF?SiO2 composite for continuous flow catalysis of important organic transformations.
Ru-g-C3N4as a highly active heterogeneous catalyst for transfer hydrogenation of α-keto amide into β-aminol or α-hydroxyl amide
Bhanage, Bhalchandra M.,Chaurasia, Shivkumar R.,Mishra, Ashish A.
supporting information, p. 10578 - 10585 (2020/07/14)
This work reports a sustainable route for the catalytic transfer hydrogenation (CTH) of α-keto amide into β-aminol via an efficient heterogeneous catalyst wherein ruthenium is incorporated on an active graphite sheet of a carbon nitride support (Ru-g-C3N4). Other different metals like Ni or Pd were also screened with the same support but none of them showed efficient activity. Although, partial hydrogenation of ketone to alcohol has also been observed based on the optimization of the reaction parameters using all of the above catalysts. The catalyst has been characterized using field emission gun scanning electron microscopy (FEG-SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infra-red (IR) spectroscopy and thermogravimetric analysis (TGA). Furthermore, the catalyst has been recycled and further characterized and does not show any significant changes in its reactivity for the CTH process. Ru-g-C3N4 as a recyclable heterogenous catalyst has been used for the first time for the CTH of α-keto amide into β-aminol, making the process sustainable because economical and environmentally benign isopropyl alcohol is used as a solvent system. The proposed catalytic system shows a wide scope of substrates for α-hydroxyamide and β-aminol derivatives, which were confirmed from 1H and 13C-NMR. This journal is
Synthesis of β-amino alcohols using the tandem reduction and ring-opening reaction of nitroarenes and epoxides
Shi, Chongyang,Ren, Cheng,Zhang, Erlei,Jin, Huile,Yu, Xiaochun,Wang, Shun
, p. 3839 - 3843 (2016/07/06)
A high yield one-pot synthesis of β-amino alcohols from nitroarenes and 1,2-epoxides was developed, which utilizes inexpensive iron dust as a reducing agent and NH4Cl as the only additive in a 50% (v/v) ethanol solution. This new efficient synthetic approach tolerates a wide range of functionalities. The mild reaction conditions (e.g., 60?°C), together with the use of low cost and readily available starting materials, make this synthetic approach an attractive alternative to the current synthesis of β-amino alcohols.
