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71.
An Immobilized‐Dirhodium Hollow‐Fiber Flow Reactor for Scalable and Sustainable C−H Functionalization in Continuous Flow 下载免费PDF全文
Chun‐Jae Yoo Dr. Daniel Rackl Wenbin Liu Caroline B. Hoyt Brian Pimentel Prof. Ryan P. Lively Prof. Huw M. L. Davies Prof. Christopher W. Jones 《Angewandte Chemie (International ed. in English)》2018,57(34):10923-10927
A scalable flow reactor is demonstrated for enantioselective and regioselective rhodium carbene reactions (cyclopropanation and C?H functionalization) by developing cascade reaction methods employing a microfluidic flow reactor system containing immobilized dirhodium catalysts in conjunction with the flow synthesis of diazo compounds. This allows the utilization of the energetic diazo compounds in a safe manner and the recycling of the dirhodium catalysts multiple times. This approach is amenable to application in a bulk‐scale synthesis employing asymmetric C?H functionalization by stacking multiple fibers in one reactor module. The products from this sequential flow–flow reactor are compared with a conventional batch reactor or flow–batch reactor in terms of yield, regioselectivity, and enantioselectivity. 相似文献
72.
Two‐Color Valence‐to‐Core X‐ray Emission Spectroscopy Tracks Cofactor Protonation State in a Class I Ribonucleotide Reductase 下载免费PDF全文
Ryan J. Martinie Dr. Elizabeth J. Blaesi Prof. Dr. J. Martin Bollinger Jr. Prof. Dr. Carsten Krebs Dr. Kenneth D. Finkelstein Dr. Christopher J. Pollock 《Angewandte Chemie (International ed. in English)》2018,57(39):12754-12758
Proton transfer reactions are of central importance to a wide variety of biochemical processes, though determining proton location and monitoring proton transfers in biological systems is often extremely challenging. Herein, we use two‐color valence‐to‐core X‐ray emission spectroscopy (VtC XES) to identify protonation events across three oxidation states of the O2‐activating, radical‐initiating manganese–iron heterodinuclear cofactor in a class I‐c ribonucleotide reductase. This is the first application of VtC XES to an enzyme intermediate and the first simultaneous measurement of two‐color VtC spectra. In contrast to more conventional methods of assessing protonation state, VtC XES is a more direct probe applicable to a wide range of metalloenzyme systems. These data, coupled to insight provided by DFT calculations, allow the inorganic cores of the MnIVFeIV and MnIVFeIII states of the enzyme to be assigned as MnIV(μ‐O)2FeIV and MnIV(μ‐O)(μ‐OH)FeIII, respectively. 相似文献
73.
The following review article provides an overview of oxidopyrylium [5+2] cycloaddition chemistry, with a particular emphasis placed on seminal historical developments and advancements made over the last decade. It is our hope this review serves as a valuable resource to those interested in the oxidopyrylium cycloaddition chemistry, and helps inspire future advancements. 相似文献
74.
Ryan J. Schwamm Dr. Mathew D. Anker Dr. Matthias Lein Dr. Martyn P. Coles Dr. Christopher M. Fitchett 《Angewandte Chemie (International ed. in English)》2018,57(20):5885-5887
Reduction of the indate complex In(NONAr)(μ‐Cl)2Li(OEt2)2 (NONAr=[O(SiMe2NAr)2]2?; Ar=2,6‐iPr2C6H3) with sodium generates the InII diindane species [In(NONAr)]2. Further reduction with a mixture of potassium and [2.2.2]crypt affords the InI N‐heterocyclic indyl anion [In(NONAr)]?, which crystallizes with a non‐contacted [K([2.2.2]crypt)]+ cation. The indyl anion can also be isolated as the indyllithium compound In(NONAr)(Li{THF}3), which contains an In?Li bond. Density functional theory calculations show that the HOMO of the indyl anion is a metal‐centred lone pair, and preliminary reactivity studies confirm its nucleophilic behaviour. 相似文献
75.
Ng YF Meillon JC Ryan T Dominey AP Davis AP Sanders JK 《Angewandte Chemie (International ed. in English)》2001,40(9):1757-1760
76.
77.
Norfloxacin, a nalidixic acid analog with antimicrobial properties, exists in different hydrated forms. Three of these crystal forms were reproducibly prepared and characterized by analytical techniques that included infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, solution microcalorimetry and pulsed nuclear-magnetic resonance spectroscopy.These studies showed that the dihydrate is the thermodynamically stable entity at ambient temperatures and humidities. 相似文献
78.
Two known papuamides C (1) and D (2) together with two new depsipeptides, papuamides E (3) and F (4), were isolated from an undescribed sponge of the genus Melophlus collected in the Solomon Islands. The planar structures of the compounds were elucidated on the basis of spectroscopic studies. Papuamides C-F (1-4) showed cytotoxicity against brine shrimp with LD50 values between 92 and 106 μg/mL. 相似文献
79.
The type 1 (T1) or blue Cu (BC) proteins are a highly studied group of electron transfer (ET) active sites in bioinorganic chemistry. In this review, we cover several more recent results which extend the understanding of the geometric and electronic structure of these interesting Cu ET sites. Spectroscopic methods in tandem with density functional theory (DFT) and time dependent-DFT (TD-DFT) calculations have been used in studies of S → Se variants as well as a series of metal-varied model complexes (M = Mn2+ → Zn2+). The ligand and metal perturbations further defined the origins of the unique spectral features of BC proteins. These unique spectral features show different temperature dependencies in different T1 sites, and contrasts drawn between their behaviors define the role of the protein in tuning the geometric and electronic structure of the BC site for function. This has been termed the ‘entatic’ or ‘rack-induced’ state in bioinorganic chemistry. 相似文献
80.