177 research outputs found

    Additive-Controlled Divergent Synthesis of Tetrasubstituted 1,3-Enynes and Alkynylated 3H-Pyrrolo[1,2-a]indol-3-ones via Rhodium Catalysis

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    Herein, we report the additive-controlled divergent synthesis of tetrasubstituted 1,3-enynes and alkynylated 3H-pyrrolo[1,2-a]indol-3-ones through rhodium-catalyzed C-H alkenylation/DG migration and [3+2] annulation, respectively. This protocol features rare directing group migration in 1,3-diyne-involved C-H activation, excellent regio- and stereoselectivity, excellent monofunctionalization over difunctionalization, broad substrate scope, moderate to high yields, good functional group compatibility, and mild redox-neutral conditions

    Temperature-Controlled Divergent Synthesis of Tetrasubstituted Alkenes and Pyrrolo[1,2-a]indole Derivatives via Iridium Catalysis

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    We have achieved an Ir(III)-catalyzed temperature-controlled divergent synthesis of tetrasubstituted alkenes and pyrrolo[1,2-a]indole derivatives through C−H alkenylation/DG migration and [3+2] annulation, respectively. This method has various advantageous features: a) excellent regio- and stereoselectivity and good functional group tolerance, b) broad substrate scope and moderate to excellent yields, c) mild redox-neutral reaction conditions and operational simplicity

    Chemo-, Regio-, and Stereoselective Assembly of Polysubstituted Furan-2(5H)-ones Enabled by Rh(III)-Catalyzed Domino C–H Alkenylation/Directing Group Migration/Lactonization: A Combined Experimental and Computational Study

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    Exploring multistep cascade reactions triggered by C–H activation are recognized as appealing, yet challenging. Herein, we disclose a Rh(III)-catalyzed domino C–H coupling of N-carbamoyl indoles and 4-hydroxy-2-alkynoates for the streamlined assembly of highly functionalized furan-2(5H)-ones in which the carbamoyl-directing group (DG) is given a dual role of an auxiliary group and a migrating acylating reagent via the cleavage of stable C–N bonds at room temperature. More importantly, the obtained furan-2(5H)-one skeleton could be further functionalized under air in situ via C5–H hydroxylation by simply switching the solvent or additive, providing fully substituted furan-2(5H)-ones with the installation of an alcohol-based C5 quaternary carbon center. Detailed experimental studies and density functional theory calculations reveal that a Rh(III)-mediated tandem C–H activation/alkyne insertion/DG migration/lactonization accounts for the developed transformation to achieve high functionalities with the observed exclusive selectivity. The potential biological application of the obtained furan-2(5H)-ones as a class of potent PPARγ ligands further highlights the synthetic utility of the developed methodology. This protocol is endowed with several salient features including efficient multistep cascade triggered by C–H activation, excellent chemo-, regio-, and stereoselectivity, high bond-forming efficiency (e.g., two C–C and two C–O bonds), solvent- or additive-controlled product selectivity, good functional-group compatibility, and mild redox-neutral conditions

    Chemo- and Regioselective Synthesis of Functionalized 1H-imidazo[1,5-a]indol-3(2H)-ones via a Redox-Neutral Rhodium(III)-Catalyzed [4+1] Annulation between Indoles and Alkynes

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    Alkynes generally serve as C2 synthons in transition-metal-catalyzed C−H annulations, herein, exploiting electron-deficient alkynes as unconventional C1 synthons, the chemo- and regiospecific synthesis of functionalized 1H-imidazo[1,5-a]indol-3(2H)-ones via a redox-neutral rhodium(III)-catalyzed [4+1] annulation of N-carbamoyl indoles has been achieved. This process is characterized by high chemo- and regioselectivity, broad substrate scope, good tolerance of functional groups, moderate to high yields and mild redox-neutral conditions, thus affording a robust approach to access valuable 1H-imidazo[1,5-a]indol-3(2H)-ones

    Observation of the Anomalous Hall Effect in a Collinear Antiferromagnet

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    Time-reversal symmetry breaking is the basic physics concept underpinning many magnetic topological phenomena such as the anomalous Hall effect (AHE) and its quantized variant. The AHE has been primarily accompanied by a ferromagnetic dipole moment, which hinders the topological quantum states and limits data density in memory devices, or by a delicate noncollinear magnetic order with strong spin decoherence, both limiting their applicability. A potential breakthrough is the recent theoretical prediction of the AHE arising from collinear antiferromagnetism in an anisotropic crystal environment. This new mechanism does not require magnetic dipolar or noncollinear fields. However, it has not been experimentally observed to date. Here we demonstrate this unconventional mechanism by measuring the AHE in an epilayer of a rutile collinear antiferromagnet RuO2_2. The observed anomalous Hall conductivity is large, exceeding 300 S/cm, and is in agreement with the Berry phase topological transport contribution. Our results open a new unexplored chapter of time-reversal symmetry breaking phenomena in the abundant class of collinear antiferromagnetic materials.Comment: 33 pages, 14 figures, 2 table

    The latest edition of WHO and ELN guidance and a new risk model for Chinese acute myeloid leukemia patients

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    ObjectiveDiagnosis classification and risk stratification are crucial in the prognosis prediction and treatment selection of acute myeloid leukemia (AML). Here, we used a database of 536 AML patients to compare the 4th and 5th WHO classifications and the 2017 and 2022 versions of ELN guidance.MethodsAML patients were classified according to the 4th and 5th WHO classifications, as well as the 2017 and 2022 versions of the European LeukemiaNet (ELN) guidance. Kaplan–Meier curves with log-rank tests were used for survival analysis.ResultsThe biggest change was that 25 (5.2%), 8 (1.6%), and 1 (0.2%) patients in the AML, not otherwise specified (NOS) group according to the 4th WHO classification, were re-classified into the AML-MR (myelodysplasia-related), KMT2A rearrangement, and NUP98 rearrangement subgroups based on the 5th WHO classification. Referring to the ELN guidance, 16 patients in the favorable group, six patients in the adverse group, and 13 patients in the intermediate group based on the 2017 ELN guidance were re-classified to the intermediate and adverse groups based on the 2022 ELN guidance. Regrettably, the Kaplan–Meier curves showed that the survival of intermediate and adverse groups could not be distinguished well according to either the 2017 or 2022 ELN guidance. To this end, we constructed a risk model for Chinese AML patients, in which the clinical information (age and gender), gene mutations (NPM1, RUNX1, SH2B3, and TP53), and fusions (CBFB::MYH11 and RUNX1::RUNX1T1) were included, and our model could help divide the patients into favorable, intermediate, and adverse groups.ConclusionThese results affirmed the clinical value of both WHO and ELN, but a more suitable prognosis model should be established in Chinese cohorts, such as the models we proposed

    Publisher Correction: An anomalous Hall effect in altermagnetic ruthenium dioxide

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    In the version of this article initially published, square brackets and parentheses were incorrect in Fig. 1g and throughout Fig. 2 (excepting lower labels in Fig. 2d–f). Further, in the second paragraph of the “Consistency with theoretical prediction” subsection of the main article, in the text now reading “the reorientation-field scale, namely, HC = (H2 AE − H2 d) /Hd,” the term “H2 AE” wasn’t shown as squared. The changes have been made in the HTML and PDF versions of the article

    Clinical Characteristics of 26 Human Cases of Highly Pathogenic Avian Influenza A (H5N1) Virus Infection in China

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    BACKGROUND: While human cases of highly pathogenic avian influenza A (H5N1) virus infection continue to increase globally, available clinical data on H5N1 cases are limited. We conducted a retrospective study of 26 confirmed human H5N1 cases identified through surveillance in China from October 2005 through April 2008. METHODOLOGY/PRINCIPAL FINDINGS: Data were collected from hospital medical records of H5N1 cases and analyzed. The median age was 29 years (range 6-62) and 58% were female. Many H5N1 cases reported fever (92%) and cough (58%) at illness onset, and had lower respiratory findings of tachypnea and dyspnea at admission. All cases progressed rapidly to bilateral pneumonia. Clinical complications included acute respiratory distress syndrome (ARDS, 81%), cardiac failure (50%), elevated aminotransaminases (43%), and renal dysfunction (17%). Fatal cases had a lower median nadir platelet count (64.5 x 10(9) cells/L vs 93.0 x 10(9) cells/L, p = 0.02), higher median peak lactic dehydrogenase (LDH) level (1982.5 U/L vs 1230.0 U/L, p = 0.001), higher percentage of ARDS (94% [n = 16] vs 56% [n = 5], p = 0.034) and more frequent cardiac failure (71% [n = 12] vs 11% [n = 1], p = 0.011) than nonfatal cases. A higher proportion of patients who received antiviral drugs survived compared to untreated (67% [8/12] vs 7% [1/14], p = 0.003). CONCLUSIONS/SIGNIFICANCE: The clinical course of Chinese H5N1 cases is characterized by fever and cough initially, with rapid progression to lower respiratory disease. Decreased platelet count, elevated LDH level, ARDS and cardiac failure were associated with fatal outcomes. Clinical management of H5N1 cases should be standardized in China to include early antiviral treatment for suspected H5N1 cases
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