Huang and Doyle explore the chemistry of transition metals with three-membered ring heterocycles, focusing on epoxides, aziridines, 2H-azirines, diaziridines, diazirines, oxaziridines, and thiiranes.
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IJS, KILJ, NUK, PNG, UL, UM
Indigo, one of the most ancient and abundant dyes in human history, has recently emerged as a potential functional motif due to its intriguing photochemical properties. This review aims to provide ...insights into both the preparation of these molecules and their utilization in molecular systems. First, the synthesis of the indigo core as well as available methods to derivatize indigo are described to outline synthetic strategies to build the desired molecular structures. Then, the photochemical behavior of indigos is discussed, with particular focus on E‐Z photoisomerization and photoinduced electron transfer. Connections between the molecular structures and their photochemical properties are highlighted and serve as guiding principles for designing indigos to be applied as photoresponsive tools.
Indigo dye is one of the most iconic compounds connecting chemistry to our society. In addition to providing the characteristic blue color, indigos display fascinating photochemical properties. This Review first discusses the synthetic construction and derivatization of indigos. Then their photoswitching and photoinduced electron transfer behaviors are described to showcase the utility of indigos as photoresponsive molecular tools.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
A Ni-catalyzed Negishi cross-coupling with 1,1-disubstituted styrenyl aziridines has been developed. This method delivers valuable β-substituted phenethylamines via a challenging reductive ...elimination that affords a quaternary carbon. A novel electron-deficient olefin ligand, Fro-DO, proved crucial for achieving high rates and chemoselectivity for C–C bond formation over β-H elimination. This ligand is easy to access, is stable, and presents a modular framework for reaction discovery and optimization. We expect that these attributes, combined with the fact that the ligands impart distinct electronic properties to a metal, will support the invention of new transformations not previously possible using established ligands.
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The blue dye indigo has historically been isolated from the plant family Indigofera and widely applied in the denim industry for producing blue jeans. The advantageous photochemical properties of ...indigo and its derivatives have now attracted the attention of the scientific community for their use as molecular photoswitches. In their review Review (DOI: 10.1002/chem.202300981), C.‐Y. Huang and S. Hecht detail the synthetic approaches to preparing indigos and discuss indigos’ applications as photoresponsive molecular tools.
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Through simple synthetic derivatisation, the parent indigo dye becomes a red-light
E
-
Z
photoswitch exhibiting negative photochromism and tuneable thermal isomerisation kinetics. These attributes ...make indigo derivatives extremely attractive for applications related to materials and living systems. However, there is a lack of knowledge in translating indigo photoswitching dynamics from solution to solid state - the environment crucial for most applications. Herein, we study the photoswitching performance of six structurally distinct indigo derivatives in five polymers of varying rigidity. Three key strategies are identified to enable efficient photoswitching under red (660 nm) light: (i) choosing a soft polymer matrix to minimise its resistance toward the isomerisation, (ii) creating free volume around the indigo molecules through synthetic modifications, and (iii) applying low dye loading (<1% w/w) to inhibit aggregation. These strategies are shown to improve both photostationary state distributions and the thermal stability of the
Z
isomer. When all three strategies are implemented, the isomerisation performance (>80%
Z
form in the photostationary state) is nearly identical to that in solution. These findings thus pave the way for designing new red-light photochromic materials based on indigos.
Through simple synthetic modifications, the indigo dye becomes an efficient red-light photoswitch - now also in the solid state.
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Herein we report a nickel-catalyzed C–C bond-forming reaction between simple alkyl aziridines and organozinc reagents. This method represents the first catalytic cross-coupling reaction employing a ...nonallylic and nonbenzylic Csp3 –N bond as an electrophile. Key to its success is the use of a new N-protecting group (cinsyl or Cn) bearing an electron-deficient olefin that directs oxidative addition and facilitates reductive elimination. Studies pertinent to elucidation of the mechanism of cross coupling are also presented.
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A nickel-catalyzed cross-coupling reaction between N-sulfonyl aziridines and organozinc reagents is reported. The catalytic system comprises an inexpensive and air-stable Ni(II) source and dimethyl ...fumarate as ligand. Regioselective synthesis of β-substituted amines is possible under mild and functional-group-tolerant conditions. The stereoselectivity of the reaction is consistent with a stereoconvergent mechanism wherein the sulfonamide directs C–C bond formation.
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Endoscopic submucosal dissection (ESD) is an established technique for the endoscopic therapy of dysplastic and early cancerous lesions throughout the gastrointestinal tract. The procedure requires ...both a sophisticated knowledge for lesion characterization and high‐level endoscopic skills. As a result, the learning curve is very steep and, in Japan, it takes years to gain proficiency under the traditional Master‐Apprentice teaching model. At present, as a result of multiple limitations, this training model is not applicable to the USA. Nevertheless, a unique, multipronged, stepwise approach has emerged as a viable pathway to train US endoscopists in ESD. Although this approach deserves refinement, it has already led to the expansion of ESD in the USA, has contributed to the widening of the indications for ESD, and has further developed ESD techniques. Multiple challenges remain, but they can be overcome by active collaboration between Japanese and US endoscopists and professional societies. The robust interest in ESD in the USA has drawn industry attention with a few innovations already coming to fruition and many more in development.
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DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
The Great Leap Forward disaster, characterized by a collapse in grain production and a widespread famine in China between 1959 and 1961, is found attributable to a systemic failure in central ...planning. Wishfully expecting a great leap in agricultural productivity from collectivization, the Chinese government accelerated its aggressive industrialization timetable. Grain output fell sharply as the government diverted agricultural resources to industry and imposed an excessive grain procurement burden on peasants, leaving them with insufficient calories to sustain labor productivity. Our analysis shows that 61 percent of the decline in output is attributable to the policies of resource diversion and excessive procurement.
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BFBNIB, CEKLJ, INZLJ, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK, ZRSKP
10.
Chronic pancreatitis Yang, Dennis; Forsmark, Chris E
Current opinion in gastroenterology,
2017-September, 2017-Sep, 2017-09-00, 20170901, Volume:
33, Issue:
5
Journal Article
Peer reviewed
PURPOSE OF REVIEWSummarize key clinical advances in chronic pancreatitis reported in 2016.
RECENT FINDINGSEarly diagnosis of chronic pancreatitis remains elusive. Recent studies suggest that ...endoscopic ultrasound may be less accurate than previously thought and new MRI techniques may be helpful. Genetic predisposition may independently affect the clinical course of chronic pancreatitis and the risk for pancreatic cancer. Cigarette smoking may have a greater negative impact on chronic pancreatitis than previously thought and moderate alcohol consumption may be protective. A multidisciplinary approach is necessary for the treatment of type 3 diabetes and nutritional deficiencies in chronic pancreatitis. Although endoscopic therapy remains a reasonable first-line option in treating chronic pancreatitis and its complications, early surgical intervention may be indicated for pain in select patients.
SUMMARYNewer endoscopic ultrasound and MRI techniques are being evaluated to help with the early diagnosis of chronic pancreatitis. Both genetic predisposition and cigarette smoking are increasingly recognized as having a major impact in the course of the disease and the risk for pancreatic cancer. Endoscopic therapy is well tolerated and effective for the treatment of chronic pancreatitis and its complications although an early surgical approach for pain may be associated with improved clinical outcomes.
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