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1.
Nature ; 2024 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-39143216

RESUMO

The newly identified type VII CRISPR-Cas candidate system uses a CRISPR RNA-guided ribonucleoprotein complex formed by Cas5 and Cas7 proteins to target RNA1. However, the RNA cleavage is executed by a dedicated Cas14 nuclease, which is distinct from the effector nucleases of the other CRISPR-Cas systems. Here we report seven cryo-electron microscopy structures of the Cas14-bound interference complex at different functional states. Cas14, a tetrameric protein in solution, is recruited to the Cas5-Cas7 complex in a target RNA-dependent manner. The N-terminal catalytic domain of Cas14 binds a stretch of the substrate RNA for cleavage, whereas the C-terminal domain is primarily responsible for tethering Cas14 to the Cas5-Cas7 complex. The biochemical cleavage assays corroborate the captured functional conformations, revealing that Cas14 binds to different sites on the Cas5-Cas7 complex to execute individual cleavage events. Notably, a plugged-in arginine of Cas7 sandwiched by a C-shaped clamp of C-terminal domain precisely modulates Cas14 binding. More interestingly, target RNA cleavage is altered by a complementary protospacer flanking sequence at the 5' end, but not at the 3' end. Altogether, our study elucidates critical molecular details underlying the assembly of the interference complex and substrate cleavage in the type VII CRISPR-Cas system, which may help rational engineering of the type VII CRISPR-Cas system for biotechnological applications.

2.
Small ; 20(24): e2308304, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38308419

RESUMO

Lithium-ion batteries (LIBs) has been developed over the last three decades. Increased amount of silicon (Si) is added into graphite anode to increase the energy density of LIBs. However, the amount of Si is limited, due to its structural instability and poor electronic conductivity so a novel approach is needed to overcome these issues. In this work, the synthesized chromium silicide (CrSi2) doped Si nanoparticle anode material achieves an initial capacity of 1729.3 mAh g-1 at 0.2C and retains 1085 mAh g-1 after 500 cycles. The new anode also shows fast charge capability due to the enhanced electronic conductivity provided by CrSi2 dopant, delivering a capacity of 815.9 mAh g-1 at 1C after 1000 cycles with a capacity degradation rate of <0.05% per cycle. An in situ transmission electron microscopy is used to study the structural stability of the CrSi2-doped Si, indicating that the high control of CrSi2 dopant prevents the fracture of Si during lithiation and results in long cycle life. Molecular dynamics simulation shows that CrSi2 doping optimizes the crack propagation path and dissipates the fracture energy. In this work a comprehensive information is provided to study the function of metal ion doping in electrode materials.

3.
Small ; 20(8): e2305991, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37858930

RESUMO

The application of Si anodes is hindered by some critical issues such as large volume changes of bare Si and fragile solid-electrolyte interface (SEI), resulting in low coulombic efficiency and rapid capacity decay. Herein, a multifunctional SEI film with high content of LiF is in situ constructed via the surface grafting of carbon-fluorine functionalized groups on silicon nanoparticles (SiNPs) during cycling. Mechanical study demonstrates that the incorporation of LiF with high modulus and unbroken carbon-fluorine groups with highly elastic guarantee the rigid-soft coupling SEI film on Si electrode. Furthermore, it is demonstrated that the rigid-soft coupling SEI film can effectively accommodate the volume expansion of Si nanoparticles during lithiation process, with the electrode expanding rate of only 114.16% after 100 cycles (263.87% for bare Si without surface modification). Afterward, with the aid of well-designed rigid-soft coupling SEI, the initial Coulomb efficiency of 89.8% is achieved, showing a reversible capacity of 1477 mAh g-1 after 200 cycles at 1.2 A g-1 . This work provides a simple and efficient solution that can potentially facilitate the practical application of Si anodes.

4.
Insect Mol Biol ; 2024 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-38801334

RESUMO

Ribosomal protein L13 (RPL13) is highly conserved in evolution. At present, the properties and functions of RPL13 have not been characterised in insects. In this study, Bombyx mori RPL13 (BmRPL13) was first found to be specifically recruited to the sites of ultraviolet (UV)-induced DNA damage and contributed to UV damage repair. Escherichia coli expressing BmRPL13 showed better resistance to UV radiation. After knocking down the expression of BmRPL13 in BmN cells, the repair speed of UV-damaged DNA slowed down. The further results showed that BmRPL13 interacted with B. mori nucleopolyhedrovirus (BmNPV) ORF65 (Bm65) protein to locate at the UV-induced DNA damage sites of BmNPV and helped repair UV-damaged viral DNA.

5.
J Appl Microbiol ; 135(3)2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38471668

RESUMO

AIMS: Enteroviruses are significant human pathogens associated with a range of mild to severe diseases. This study aims to understand the diversity and genetic characterization of enteroviruses circulated in southwest China's border cities by using environmental surveillance. METHODS AND RESULTS: A total of 96 sewage samples were collected in three border cities and a port located in Yunnan Province, China from July 2020 to June 2022. After cell culture and VP1 sequencing, a total of 590 enterovirus isolates were identified, belonging to 21 types. All PV strains were Sabin-like with ≤6 nucleotide mutations in the VP1 coding region. Echovirus 6, echovirus 21 (a rare serotype in previous studies), and coxsackievirus B5 were the predominant serotypes, which accounted for 21.19%, 18.31%, and 13.39% of the total isolates, respectively. The prevalence of the common serotypes varied across different border cities and periods. Phylogenetic analysis revealed the presence of multiple evolutionary lineages for E21, E6, and E30, some of which formed distinct branches. CONCLUSIONS: High diversity of enteroviruses and distinct lineages of predominant serotypes circulated in southwest China's border cities.


Assuntos
Infecções por Enterovirus , Enterovirus , Humanos , Cidades , Filogenia , China/epidemiologia , Infecções por Enterovirus/epidemiologia , Enterovirus Humano B/genética , Antígenos Virais/genética , Monitoramento Ambiental/métodos
6.
Proc Natl Acad Sci U S A ; 118(51)2021 12 21.
Artigo em Inglês | MEDLINE | ID: mdl-34903655

RESUMO

Short-term forecasts of traditional streams from public health reporting (such as cases, hospitalizations, and deaths) are a key input to public health decision-making during a pandemic. Since early 2020, our research group has worked with data partners to collect, curate, and make publicly available numerous real-time COVID-19 indicators, providing multiple views of pandemic activity in the United States. This paper studies the utility of five such indicators-derived from deidentified medical insurance claims, self-reported symptoms from online surveys, and COVID-related Google search activity-from a forecasting perspective. For each indicator, we ask whether its inclusion in an autoregressive (AR) model leads to improved predictive accuracy relative to the same model excluding it. Such an AR model, without external features, is already competitive with many top COVID-19 forecasting models in use today. Our analysis reveals that 1) inclusion of each of these five indicators improves on the overall predictive accuracy of the AR model; 2) predictive gains are in general most pronounced during times in which COVID cases are trending in "flat" or "down" directions; and 3) one indicator, based on Google searches, seems to be particularly helpful during "up" trends.


Assuntos
COVID-19/epidemiologia , Indicadores Básicos de Saúde , Modelos Estatísticos , Métodos Epidemiológicos , Previsões , Humanos , Internet/estatística & dados numéricos , Inquéritos e Questionários , Estados Unidos/epidemiologia
7.
Proc Natl Acad Sci U S A ; 118(51)2021 12 21.
Artigo em Inglês | MEDLINE | ID: mdl-34903654

RESUMO

The COVID-19 pandemic presented enormous data challenges in the United States. Policy makers, epidemiological modelers, and health researchers all require up-to-date data on the pandemic and relevant public behavior, ideally at fine spatial and temporal resolution. The COVIDcast API is our attempt to fill this need: Operational since April 2020, it provides open access to both traditional public health surveillance signals (cases, deaths, and hospitalizations) and many auxiliary indicators of COVID-19 activity, such as signals extracted from deidentified medical claims data, massive online surveys, cell phone mobility data, and internet search trends. These are available at a fine geographic resolution (mostly at the county level) and are updated daily. The COVIDcast API also tracks all revisions to historical data, allowing modelers to account for the frequent revisions and backfill that are common for many public health data sources. All of the data are available in a common format through the API and accompanying R and Python software packages. This paper describes the data sources and signals, and provides examples demonstrating that the auxiliary signals in the COVIDcast API present information relevant to tracking COVID activity, augmenting traditional public health reporting and empowering research and decision-making.


Assuntos
COVID-19/epidemiologia , Bases de Dados Factuais , Indicadores Básicos de Saúde , Assistência Ambulatorial/tendências , Métodos Epidemiológicos , Humanos , Internet/estatística & dados numéricos , Distanciamento Físico , Inquéritos e Questionários , Viagem , Estados Unidos/epidemiologia
8.
BMC Med Inform Decis Mak ; 24(1): 224, 2024 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-39118122

RESUMO

OBJECTIVE: To develop a machine learning-based risk prediction model for postoperative parastomal hernia (PSH) in colorectal cancer patients undergoing permanent colostomy, assisting nurses in identifying high-risk groups and devising preventive care strategies. METHODS: A case-control study was conducted on 495 colorectal cancer patients who underwent permanent colostomy at the Second Affiliated Hospital of Anhui Medical University from June 2017 to June 2023, with a 1-year follow-up period. Patients were categorized into PSH and non-PSH groups based on PSH occurrence within 1-year post-operation. Data were split into training (70%) and testing (30%) sets. Variable selection was performed using Least Absolute Shrinkage and Selection Operator (LASSO) regression, and binary classification prediction models were established using Logistic Regression (LR), Support Vector Classification (SVC), K Nearest Neighbor (KNN), Random Forest (RF), Light Gradient Boosting Machine (LGBM), and Extreme Gradient Boosting (XgBoost). The binary classification label denoted 1 for PSH occurrence and 0 for no PSH occurrence. Parameters were optimized via 5-fold cross-validation. Model performance was evaluated using Area Under Curve (AUC), specificity, sensitivity, accuracy, positive predictive value, negative predictive value, and F1-score. Clinical utility was evaluated using decision curve analysis (DCA), model explanation was enhanced using shapley additive explanation (SHAP), and model visualization was achieved using a nomogram. RESULTS: The incidence of PSH within 1 year was 29.1% (144 patients). Among the models tested, the RF model demonstrated the highest discrimination capability with an AUC of 0.888 (95% CI: 0.881-0.935), along with superior specificity, accuracy, sensitivity, and F1 score. It also showed the highest clinical net benefit on the DCA curve. SHAP analysis identified the top 10 influential variables associated with PSH risk: body mass index (BMI), operation duration, history and status of chronic obstructive pulmonary disease (COPD), prealbumin, tumor node metastasis (TNM) staging, stoma site, thickness of rectus abdominis muscle (TRAM), C-reactive protein CRP, american society of anesthesiologists physical status classification (ASA), and stoma diameter. These insights from SHAP plots illustrated how these factors influence individual PSH outcomes. The nomogram was used for model visualization. CONCLUSION: The Random Forest model demonstrated robust predictive performance and clinical relevance in forecasting colonic PSH. This model aids in early identification of high-risk patients and guides preventive care.


Assuntos
Neoplasias Colorretais , Colostomia , Aprendizado de Máquina , Humanos , Feminino , Masculino , Colostomia/efeitos adversos , Pessoa de Meia-Idade , Estudos de Casos e Controles , Neoplasias Colorretais/cirurgia , Idoso , Medição de Risco , Complicações Pós-Operatórias , Hérnia Incisional/etiologia , Algoritmos
9.
Small ; 19(7): e2204690, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36494156

RESUMO

Silicon is an excellent candidate for the next generation of ultra-high performance anode materials, with the rapid iteration of the lithium-ion battery industry. High-quality silicon sources are the cornerstone of the development of silicon anodes, and silicon cutting waste (SCW) is one of them while still faces the problems of poor performance and unclear structure-activity relationship. Herein, a simple, efficient, and inexpensive purification method is implemented to reduce impurities in SCW and expose the morphology of nanosheets therein. Furthermore, HF is used to modulate the abundant native O in SCW after thermodynamic and kinetic considerations, realizing the mechanical support for the internal Si in the form of an amorphous SiO2 shell. Afterward, SCNS@SiO2 -2.5 with a 1.0 nm thick SiO2 shell exhibits a reversible capacity of 1583.3 mAh g-1 after 200 cycles at 0.8 A g-1 . Ultimately, the molecular dynamics simulations profoundly reveal that the amorphous SiO2 shell is transformed into the extremely ductile Lix SiOy shell to ditch stress and relieve strain during the lithiation/delithiation process.

10.
J Virol ; 96(14): e0055722, 2022 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-35862702

RESUMO

Baculoviruses have been used as biopesticides for the control of Lepidoptera larvae. However, solar UV radiation reduces the activity of baculovirus. In this study, an UV endonuclease, Bm65, was found encoded in the genome of Bombyx mori nuclear polyhedrosis virus (BmNPV). Bm65 (the ortholog of AcMNPV orf79) was guided by a key nuclear localization signal to enter the nucleus and accumulated at UV-induced DNA damage sites. Subsequent results further showed that Bm65-mediated DNA damage repair was not the only UV damage repair pathway of BmNPV. BmNPV also used host DNA repair proteins to repair UV-induced DNA damage. In summary, these results revealed that Bm65 was very important in UV-induced DNA damage repair of BmNPV, and BmNPV repaired UV-damaged DNA through a variety of ways. IMPORTANCE Baculovirus biopesticides are environmentally friendly insecticides and specifically infect invertebrates. UV radiation from the sunlight greatly reduces the activity of baculovirus biopesticides. However, the molecular mechanisms of most baculoviruses to repair UV-induced DNA damage remain unclear. Nucleotide excision repair (NER) is a major DNA repair pathway that removes UV-induced DNA lesions. At present, there are few reports about the nucleotide excision repair pathway in viruses. Here, we showed for the first time that the baculovirus Bm65 endonuclease actually cleaved UV-damaged DNA. Meanwhile, we found that BmNPV used both viral-encoded enzymes and host DNA damage repair proteins to reverse UV-induced DNA damage. These results will provide a reference for the research of UV damage repair of other viruses.


Assuntos
Dano ao DNA , Reparo do DNA , Endonucleases , Nucleopoliedrovírus , Animais , Agentes de Controle Biológico/metabolismo , Bombyx , Dano ao DNA/efeitos da radiação , Endonucleases/genética , Nucleopoliedrovírus/genética , Nucleopoliedrovírus/metabolismo , Raios Ultravioleta
11.
J Org Chem ; 88(14): 9783-9790, 2023 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-37386789

RESUMO

A visible-light-driven Mn-catalyzed C(sp3)-H amidation of diphenylmethane derivatives with dioxazolones was described. These reactions occur with an external photosensitizer-free process and feature satisfactory to good yields (up to 81%) under mild conditions. Mechanistic investigations revealed that the reaction proceeded via a Mn-acyl nitrene intermediate and that H-atom abstraction was the rate-determining step. Computational studies showed that the decarboxylation of dioxazolone depends on the conversion of ground sextet state dioxazolone-bounding Mn species to quartet spin state via visible-light irradiation.

12.
Nanotechnology ; 34(15)2023 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-36649649

RESUMO

Battery safety calls for solid state batteries and how to prepare solid electrolytes with excellent performance are of significant importance. In this study, hybrid solid electrolytes combined with organic PVDF-HFP and inorganic active fillers are studied. The modified active fillers of Li7-x-3yAlyLa3Zr2-xTaxO12are obtained by co-element doping with Al and Ta when LLZO is synthesized by calcination. And an high room temperature ionic conductivity of 5.357 × 10-4S cm-1is exhibited by ATLLZO ceramic sheet. The composite solid electrolyte PVDF-HFP/LiTFSI/ATLLZO (PHL-ATLLZO) is prepared by solution casting method, and its electrochemical properties are investigated. The results show that when the contents of lithium salt LiTFSI and active filler ATLLZO are controlled at 40 wt% and 10%, respectively, the ionic conductivity of the resulting composite solid electrolyte is as high as 2.686 × 10-4S cm-1at room temperature, and a wide electrochemical window of 4.75 V is exhibited. The LiFePO4/PHL-ATLLZO/Li all-solid-state battery assembled based on the composite solid-state electrolyte exhibits excellent cycling stability at room temperature. The cell assembled by casting the composite solid-state electrolyte on the cathode surface shows a discharge specific capacity of 134.3 mAh g-1and 96.2% capacity retention after 100 cycles at 0.2 C. The prepared composite solid-state electrolyte demonstrates excellent electrochemical performance.

13.
BMC Endocr Disord ; 23(1): 213, 2023 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-37798680

RESUMO

BACKGROUND: Idiopathic hypogonadotropic hypogonadism (IHH) is a rare congenital or acquired genetic disorder caused by gonadotropin-releasing hormone (GnRH) deficiency. IHH patients are divided into two major groups, hyposmic or anosmic IHH (Kallmann syndrome) and normosmic IHH (nIHH), according to whether their sense of smell is intact. Here we report a case of novel compound heterozygous mutations in the GNRH1 gene in a 15-year-old male with nIHH. CASE PRESENTATION: The patient presented typical clinical symptoms of delayed testicular development, with testosterone < 3.5 mmol/L and reduced gonadotropin (follicle-stimulating hormone, luteinizing hormone) levels. Two heterozygous variants of the GNRH1 gene were detected, nonsense variant 1: c.85G > T:p.G29* and variant 2: c.1A > G:p.M1V, which disrupted the start codon. CONCLUSIONS: Two GNRH1 mutations responsible for nIHH are identified in this study. Our findings extend the mutational spectrum of GNRH1 by revealing novel causative mutations of nIHH.


Assuntos
Hormônio Liberador de Gonadotropina , Hipogonadismo , Adolescente , Humanos , Masculino , Hormônio Liberador de Gonadotropina/genética , Hipogonadismo/genética , Hipogonadismo/diagnóstico , Síndrome de Kallmann/genética , Mutação , Testosterona/análise
16.
Inorg Chem ; 61(49): 20035-20042, 2022 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-36427263

RESUMO

Based on luminescence intensity ratio (LIR) technology, the noncontact upconversion (UC) optical temperature sensor has aroused a great deal of interest due to its great application prospects in some extreme environments. However, most of the studies focused on improving its sensitivity due to the fact that the sensitivity can be influenced by many external field factors, such as the power density and pulse width of pumping sources or temperature. Herein, a green-emitting UC phosphor Sr2InF7: Yb3+, Er3+ was developed as a potential thermometer, which retained bright green emission under 980 nm excitation with different pulse widths and power densities or at different temperatures; the possible mechanisms are discussed in detail. Its sensitivity almost remained constant when using both continuous wave (c.w.) and pulsed laser or different power densities, which meant the sensitivity of Sr2InF7: Yb3+, Er3+ was independent of the characteristics of pumping laser. A flexible thin-film thermometer composed of Sr2InF7: 2%Yb3+, 2%Er3+ was also fabricated to detect the temperature of microelectronic components, which can not only accurately measure the temperature of the working electronic circuit board but also exhibit excellent repeatability. The results indicated that the present noncontact UC temperature sensor showed stable green emission and thermometric sensitivity as well as the possibility of replacing the traditional thermometers.


Assuntos
Luz , Luminescência , Temperatura , Eletrônica
17.
Neoplasma ; 69(6): 1373-1385, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36353938

RESUMO

Aberrant DNA methylation of genes is closely linked to many aspects of tumor development. This study focuses on the effect of DNA hypermethylation of von Willebrand factor C domain containing 2 (VWC2) on colorectal cancer (CRC) progression and the underpinning mechanism. According to data in the bioinformatic systems, VWC2 had the highest degree of DNA methylation in colonic adenocarcinoma, and it showed DNA hypermethylation in rectal adenocarcinoma as well. CRC and the para-tumorous tissues were collected from 86 patients. VWC2 was expressed at low levels in CRC samples and inversely correlated with tumor stage and tumor biomarker expression. DNA hypermethylation and reduced expression of VWC2 were also detected in CRC cell lines HCT-116 and HT29. VWC2 overexpression suppressed the malignant growth of cells in vitro and in vivo. Co-immunoprecipitation and western blot assays showed that small ubiquitin-like modifier 1 (SUMO1) mediated SUMOylation of DNA methyltransferase 1 (DNMT1) and strengthened its protein stability, which promoted DNA methylation and suppression of the VWC2 gene. In summary, this study demonstrates that SUMO1-mediated activation of DNMT1 induces DNA methylation and downregulation of VWC2 in CRC to augment cancer development.


Assuntos
Adenocarcinoma , Neoplasias Colorretais , Humanos , Metilação de DNA , Neoplasias Colorretais/patologia , DNA , Metiltransferases/genética , Adenocarcinoma/genética , Regulação Neoplásica da Expressão Gênica , Proteína SUMO-1/genética , Proteína SUMO-1/metabolismo
18.
J Cell Physiol ; 236(6): 4231-4243, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33241566

RESUMO

MicroRNA-128 (miR-128) is associated with cell proliferation, differentiation, migration, apoptosis, and survival. Genetic analysis studies have demonstrated that miR-128 participates in bone metabolism, which involves bone marrow-derived mesenchymal stem cells, osteoblasts, osteoclasts, and adipocytes. miR-128 also participates in regeneration of skeletal muscles by targeting myoblast-associated proteins. The deregulation of miR-128 could lead to a series of musculoskeletal diseases. In this review, we discuss recent findings of miR-128 in relation to bone metabolism and muscle regeneration to determine its potential therapeutic effects in musculoskeletal diseases, and to propose directions for future research in this significant field.


Assuntos
Remodelação Óssea , MicroRNAs/metabolismo , Desenvolvimento Muscular , Doenças Musculoesqueléticas/metabolismo , Sistema Musculoesquelético/metabolismo , Osteogênese , Artrite/genética , Artrite/metabolismo , Artrite/fisiopatologia , Remodelação Óssea/genética , Exossomos/genética , Exossomos/metabolismo , Regulação da Expressão Gênica , Humanos , Masculino , MicroRNAs/genética , Desenvolvimento Muscular/genética , Doenças Musculoesqueléticas/genética , Doenças Musculoesqueléticas/fisiopatologia , Sistema Musculoesquelético/fisiopatologia , Osteogênese/genética , Osteoporose/genética , Osteoporose/metabolismo , Osteoporose/fisiopatologia
19.
Inorg Chem ; 60(15): 11661-11671, 2021 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-34282615

RESUMO

Electrochemical water splitting is regarded as the most potential sustainable hydrogen production technology. However, the slow reaction kinetics and high overpotential of this process will result in low energy conversion efficiency. Therefore, it is of great practical value to research low-cost, efficient, and stable transition-metal-based bifunctional electrocatalysts. Herein, Fe-Co Prussian blue analogue (PBA) was coated with Ni-Co PBA to prepare the trimetallic PBA precursor, and the trimetallic phosphate (Fe-Co-Ni-P-1) has been prepared via the low-temperature phosphating process. The effects of metal ratios, the amount of sodium hypophosphite, and phosphating temperature on the catalytic performances were studied. When Fe-Co-Ni-P-1 was used as an electrocatalyst, the overpotential of oxygen evolution reaction and hydrogen evolution reaction was 247 and 215 mV, respectively, at a current density of 10 mA cm-2. At the same time, Fe-Co-Ni-P-1 showed faster kinetics and better long-term stability in the catalytic process. The catalytic performances of unary metal, binary metal, and ternary metal phosphides, oxides, and sulfides were systematically studied. It is demonstrated that the ternary metal phosphide Fe-Co-Ni-P-1 manifests the best catalytic performance, which is mainly attributed to the monodisperse core-shell structure, low resistance, large electrochemical active area, and the synergistic effect among metals.

20.
Angew Chem Int Ed Engl ; 60(30): 16426-16435, 2021 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-33843125

RESUMO

Herein, visible-light-driven iron-catalyzed nitrene transfer reactions with dioxazolones for intermolecular C(sp3 )-N, N=S, and N=P bond formation are described. These reactions occur with exogenous-ligand-free process and feature satisfactory to excellent yields (up to 99 %), an ample substrate scope (109 examples) under mild reaction conditions. In contrast to intramolecular C-H amidations strategies, an intermolecular regioselective C-H amidation via visible-light-induced nitrene transfer reactions is devised. Mechanistic studies indicate that the reaction proceeds via a radical pathway. Computational studies show that the decarboxylation of dioxazolone depends on the conversion of ground sextet state dioxazolone-bounding iron species to quartet spin state via visible-light irradiation.

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