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1.
BMC Musculoskelet Disord ; 25(1): 324, 2024 Apr 24.
Artículo en Inglés | MEDLINE | ID: mdl-38658870

RESUMEN

BACKGROUND: Hip hemiarthroplasty has traditionally been used to treat displaced femoral neck fractures in older, frailer patients whilst total hip replacements (THR) have been reserved for younger and fitter patients. However, not all elderly patients are frail, and some may be able to tolerate and benefit from an acute THR. Nonagenarians are a particularly heterogenous subpopulation of the elderly, with varying degrees of independence. Since THRs are performed electively as a routine treatment for osteoarthritis in the elderly, its safety is well established in the older patient. The aim of this study was to compare the safety of emergency THR to elective THR in nonagenarians. METHODS: A retrospective 10-year cohort study was conducted using data submitted to the National Hip Fracture Database (NHFD) across three hospitals in one large NHS Trust. Data was collected from 126 nonagenarians who underwent THRs between 1st January 2010 - 31st December 2020 and was categorised into emergency THR and elective THR groups. Mortality rates were compared between the two groups. Secondary outcomes were also compared including postoperative complications (dislocations, revision surgeries, and periprosthetic fracture), length of stay in hospital, and discharge destination. RESULTS: There was no significant difference in mortality between the two groups, with 1-year mortality rates of 11.4% and 12.1% reported for emergency and elective patients respectively (p = 0.848). There were no significant differences in postoperative complication rate and discharge destination. Patients who had emergency THR spent 5.56 days longer in hospital compared to elective patients (p = 0.015). CONCLUSION: There is no increased risk of 1-year mortality in emergency THR compared to elective THR, in a nonagenarian population. Therefore, nonagenarians presenting with a hip fracture who would have been considered for a THR if presenting on an elective basis should not be precluded from an emergency THR on safety grounds. TRIAL REGISTRATION: Not necessary as this was deemed not to be clinical research, and was considered to be a service evaluation.


Asunto(s)
Artroplastia de Reemplazo de Cadera , Procedimientos Quirúrgicos Electivos , Fracturas del Cuello Femoral , Complicaciones Posoperatorias , Humanos , Fracturas del Cuello Femoral/cirugía , Fracturas del Cuello Femoral/mortalidad , Artroplastia de Reemplazo de Cadera/efectos adversos , Femenino , Masculino , Anciano de 80 o más Años , Estudios Retrospectivos , Procedimientos Quirúrgicos Electivos/efectos adversos , Complicaciones Posoperatorias/epidemiología , Complicaciones Posoperatorias/etiología , Resultado del Tratamiento , Tiempo de Internación/estadística & datos numéricos , Reoperación/estadística & datos numéricos
2.
J Family Med Prim Care ; 13(2): 704-712, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38605810

RESUMEN

Background: The transportation system plays a crucial role in the context of socioeconomic development, whereas the highway infrastructure acts as a base for the transportation system. In recent years, a rich impetus has been given to the development of road infrastructure by Indian governance. There is a need to introspect how well the prevailing highway infrastructure is equipped with emergency rescue management during road accidents. Lack of ambulance service and trauma facilities along the highways results in a steady loss of lives and injuries and increases people's exposure to risks. Objective: This study aims to determine the response time of ambulance reachability to the accident spot on Indian national highways associated with heavy commercial transportation. Also, determining the time to transport the injured to the nearest trauma facility is another factor included as an objective in this investigation. Methods: The study adopted survey-based research, whereby the variables in the questionnaire were designed to record and assess the time for an ambulance to reach the accident spot and, from there, to transport the injured to the trauma management facility on Indian highways. Two hundred twenty-five participants who were either victims/relatives of victims or those involved in the rescue of the injured have participated in the survey. The dates of the accident events were 2017 and 2022. Results: The survey resulted in the identification of two categories of highway accidents. The first category of accidents happened on the highways near city limits/dense settlements, and the second category occurred on the core highways. The percentage of accidents caused on the highways either adjacent to or passing through the city limits/dense settlements was reported to be higher than the accidents on the core highways. Ninety percent of the participants reported successful contact with the ambulance call/service centre, but only ~75% success rate exists for ambulances to reach the accident scene. On the core highways, the time taken for the ambulance to arrive at the accident scene is 25-35 minutes. The results from the survey ascertained that the patients were prioritised for treatment in the nearest hospitals (irrespective of having a trauma facility) at a distance of ~12-20 km, for which the time taken is ~15-25 minutes. Importantly, from the interviews, it is understood that in many cases, these hospitals have further referred to specialty hospitals located in nearby cities or trauma centres with greater facilities. Occasions exist where the injured were taken directly to hospitals 30-40 km from the accident spot, for which the time was more than 40 minutes. Conclusions: The results provide evidence that in either of the accident cases on the highways that are adjacent to/passing through the city limits or on the core highways, the total time for emergency care accessibility is nearly 60 minutes or greater; this implies that in the majority of cases, there is very meagre time left to provide emergency medical care to the needy and injured on the Indian highways to abide by the concept of golden hour. Plausible reforms backed by technology for enabling highways into 'emergency rescuable highways' are highly needed to guarantee a safer and more sustainable transportation system in India.

3.
Chem Commun (Camb) ; 60(9): 1188-1191, 2024 Jan 25.
Artículo en Inglés | MEDLINE | ID: mdl-38193881

RESUMEN

A versatile, robust, and stable tetrabutylammonium difluorotriphenylsilicate (TBAT) catalyst has been deployed for efficient depolymerization of silicones. This catalyst is soluble in a variety of organic solvents and is stable up to 170 °C, enabling a wide range of reaction conditions under which F--catalysed siloxane bond cleavage can be initiated. This effort offers significant advancement overcoming the traditional limitations of silicone depolymerization, such as high catalyst loading, storage and handling, and few viable reaction media.

4.
Sci Transl Med ; 15(719): eadg5252, 2023 10 25.
Artículo en Inglés | MEDLINE | ID: mdl-37878672

RESUMEN

Effective tissue repair requires coordinated intercellular communication to sense damage, remodel the tissue, and restore function. Here, we dissected the healing response in the intestinal mucosa by mapping intercellular communication at single-cell resolution and integrating with spatial transcriptomics. We demonstrated that a risk variant for Crohn's disease, hepatocyte growth factor activator (HGFAC) Arg509His (R509H), disrupted a damage-sensing pathway connecting the coagulation cascade to growth factors that drive the differentiation of wound-associated epithelial (WAE) cells and production of a localized retinoic acid (RA) gradient to promote fibroblast-mediated tissue remodeling. Specifically, we showed that HGFAC R509H was activated by thrombin protease activity but exhibited impaired proteolytic activation of the growth factor macrophage-stimulating protein (MSP). In Hgfac R509H mice, reduced MSP activation in response to wounding of the colon resulted in impaired WAE cell induction and delayed healing. Through integration of single-cell transcriptomics and spatial transcriptomics, we demonstrated that WAE cells generated RA in a spatially restricted region of the wound site and that mucosal fibroblasts responded to this signal by producing extracellular matrix and growth factors. We further dissected this WAE cell-fibroblast signaling circuit in vitro using a genetically tractable organoid coculture model. Collectively, these studies exploited a genetic perturbation associated with human disease to disrupt a fundamental biological process and then reconstructed a spatially resolved mechanistic model of tissue healing.


Asunto(s)
Enfermedad de Crohn , Ratones , Humanos , Animales , Enfermedad de Crohn/genética , Enfermedad de Crohn/metabolismo , Transducción de Señal , Células Epiteliales/metabolismo , Mucosa Intestinal/metabolismo , Diferenciación Celular
5.
Nano Lett ; 23(20): 9474-9481, 2023 Oct 25.
Artículo en Inglés | MEDLINE | ID: mdl-37831934

RESUMEN

We report a spontaneous and hierarchical self-assembly mechanism of carbon dots prepared from citric acid and urea into nanowire structures with large aspect ratios (>50). Scattering-type scanning near-field optical microscopy (s-SNOM) with broadly tunable mid-IR excitation was used to interrogate details of the self-assembly process by generating nanoscopic chemical maps of local wire morphology and composition. s-SNOM images capture the evolution of wire formation and the complex interplay between different chemical constituents directing assembly over the nano- to microscopic length scales. We propose that residual citrate promotes tautomerization of melamine surface functionalities to produce supramolecular shape synthons comprised of melamine-cyanurate adducts capable of forming long-range and highly directional hydrogen-bonding networks. This intrinsic, heterogeneity-driven self-assembly mechanism reflects synergistic combinations of high chemical specificity and long-range cooperativity that may be harnessed to reproducibly fabricate functional structures on arbitrary surfaces.

6.
Animals (Basel) ; 13(16)2023 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-37627421

RESUMEN

The effects of Bacillus spp. (7 Log CFU g-1 feed) and fructooligosaccharide (FOS, 1%) as functional feed additives, either alone or in combination, were evaluated in a study on rohu, Labeo rohita fingerlings. The fish were fed different diets for 90 days, including a control diet and diets supplemented with FOS, B. licheniformis, B. methylotrophicus or synbiotic formulations of these. The results showed that the combination of B. licheniformis and FOS significantly improved weight gain, feed utilisation and protease activity compared to the other groups. Overall, the groups supplemented with probiotics and synbiotics (B. licheniformis + FOS or B. methylotrophicus + FOS) showed improvements in haematology, serum biochemistry and immune parameters compared to the control group. After 90 days of experimental feeding, the fish were challenged with pathogenic Aeromonas hydrophila, and data on haematology, immunity and stress parameters were collected. The results indicated that the application of Bacillus spp. and FOS boosted immunity and resistance to physiological stress in the fish. The highest post-challenge survival rate was observed in fish fed a diet with B. licheniformis and FOS, indicating the potential of this particular combination of functional feed additives to enhance growth, immunity and disease resistance in L. rohita.

7.
Nanoscale ; 15(33): 13809-13821, 2023 Aug 25.
Artículo en Inglés | MEDLINE | ID: mdl-37578279

RESUMEN

Two-dimensional (2D) semiconducting material-based photodetectors (PDs) with high responsivity and fast photo-response are of great interest for various applications such as optical communications, biomedical imaging, security surveillance, environmental monitoring, etc. Additive manufacturing such as 2D printing is a potentially less cumbersome and cost-effective alternative to conventional microdevice fabrication processes used in the production of PDs. Here, we have fabricated a Si/WS2 quantum dot-based heterostructure PD with a very short electrode gap of 40 µm by a simple printing process. The printed p-Si/n-WS2 PD shows an excellent photo-to-dark current ratio of 5121 under 405 nm illumination (23.8 mW cm-2). The printed photodetector exhibits a peak responsivity of 126 A W-1 and a peak detectivity of 9.24 × 1012 Jones over a very broad wavelength range (300-1100 nm), which is much superior to commercial Si PDs. A high external quantum efficiency of 3.9 × 104% and an ultrafast photoresponse (7.8 µs rise time and 9.5 µs fall time) make the device an attractive candidate as an efficient photodetector. The origin of high-performance photodetection is traced to a nearly defect-free interface at the heterojunction, leading to highly efficient charge separation and high photocurrent. Finally, the 2D-printed device exhibits good photodetection even in self-powered conditions, which is very attractive.

8.
J Med Entomol ; 60(2): 373-383, 2023 03 06.
Artículo en Inglés | MEDLINE | ID: mdl-36744984

RESUMEN

During larval rearing of Culicoides peregrinus Kieffer (Diptera: Ceratopogonidae) it was obligatory to add a small quantity of mud from larval habitat to nutrient broth in culture plates. This initiated microbial growth in rearing plates which facilitated growth and development of immature. The primary aim was to enumerate gut microbial communities across the different life stages of C. peregrinus. Amplicon sequencing of the V3-V4 hypervariable region (16S rDNA) was done on Illumina Miseq platform to detect gut bacterial communities at different life stages, while ITS regions (18S rRNA) were targeted for fungal communities of the 4th instar larvae. The major findings were: 1) Phylum Proteobacteria and Firmicutes were the most abundant throughout the life stages, along with the highest bacterial alpha diversity in the egg, 2) bacterial compositions were similar to laboratory reared and field collected adults, and 3) abundant fungal phyla associated with the larval gut were Ascomycota and Basidiomycota. Furthermore, analyses of the gut microbiome with METAGENassist might be indicative of their likely function in the natural habitat. Abundant gut-associated bacteria and/or fungal genera detected in the present study could be used as dietary supplements to establish laboratory colonies for further vectorial research. While, individual roles of the bacteria or fungi in paratransgenesis are warned for their possible utilization to frame the management strategy in upcoming works.


Asunto(s)
Virus de la Lengua Azul , Ceratopogonidae , Microbiota , Animales , Bacterias/genética , Larva
9.
Animals (Basel) ; 12(21)2022 Nov 03.
Artículo en Inglés | MEDLINE | ID: mdl-36359140

RESUMEN

The present paper presents an overview of the effects of gut microbiota and probiotics on lipid-, carbohydrate-, protein- and amino acid metabolism in fish and shrimp. In probiotic fish studies, the zebrafish (Danio rerio) model is the most frequently used, and probiotic administration reveals the effect on glucose homeostasis, anti-lipidemic effects and increasing short-chain fatty acids, and increased expressions of genes related to carbohydrate metabolism and innate immunity, along with down-regulation of oxidative stress-related genes. Further, improved length of the intestinal villi and expression of nutrient transporters in fish owing to probiotics exposure have been documented. The present review will present an appraisal of the effect of intestinal microbiota and probiotic administration on the metabolism of nutrients and metabolites related to stress and immunity in diverse fish- and shrimp species. Furthermore, to give the reader satisfactory information on the topics discussed, some information from endothermic animals is also presented.

10.
Eur Phys J Spec Top ; 231(18-20): 3505-3535, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35789684

RESUMEN

In the present work, a study has been made over the prime stock indices of some fiscally prominent countries impacted by COVID-19. The countries are separated in two ways: (1) considering gross total number of infected cases-here seven mostly impacted countries with certain global economic influence are selected; (2) considering the concentration of the infected cases-here six major impacted countries with considerable influence are selected. This sort of categorization is itself a novel strategy which is capable of including some less populated, but severely impacted countries of economic importance. The objective of the present analysis is to comprehend the impact of COVID-19 on these markets and to recognize the effect of COVID-19 on mutual association and dependence between these markets. To add more flavour of reliability, we have taken a new and fresh strategy of fixing the time frames under consideration before and during COVID-19 pandemic as uniform. We have used both linear and nonlinear Granger causality analysis and employed generalized forecast error variance decomposition analysis to review the exogeneity and endogeneity of the individual markets. The present study shows that this pandemic has changed the underlying relationship: some exogenous stock markets have become endogenous and vice versa in the pandemic. Linear relationship has been reduced radically, whereas nonlinear relationship has been improved during the COVID-affected period. TASE, the highest returned and significantly uncorrelated index, emerged as the most exogenous market in the pre-COVID period, though it is nonlinearly endogenous in the long term, in the COVD-affected period. CAC 40 is the most endogenous market for the short term in both pre-COVID and COVID-affected period. B3 and NYSE, exogenous in the pre-COVID period, turned out to be linearly endogenous in the COVID-affected duration, whereas BIST 100 and BSE SENSEX are found to be exogenous markets in the COVID-affected period according to both linear and nonlinear causal analysis. They were also exogenous in the pre-COVID era for the short-term period, with BSE SENSEX exhibiting exogeneity anti-persistently for the COVID-affected period too. Association among the markets is more in long term rather than short term. A possible conclusion is also that the markets may regain long-term association once the effect of COVID would fade away.

11.
Environ Microbiome ; 17(1): 32, 2022 Jun 24.
Artículo en Inglés | MEDLINE | ID: mdl-35739580

RESUMEN

It is undeniable that plastics are ubiquitous and a threat to global ecosystems. Plastic waste is transformed into microplastics (MPs) through physical and chemical disruption processes within the aquatic environment. MPs are detected in almost every environment due to their worldwide transportability through ocean currents or wind, which allows them to reach even the most remote regions of our planet. MPs colonized by biofilm-forming microbial communities are known as the ''plastisphere". The revelation that this unique substrate can aid microbial dispersal has piqued interest in the ground of microbial ecology. MPs have synergetic effects on the development, transportation, persistence, and ecology of microorganisms. This review summarizes the studies of plastisphere in recent years and the microbial community assemblage (viz. autotrophs, heterotrophs, predators, and pathogens). We also discussed plastic-microbe interactions and the potential sources of plastic degrading microorganisms. Finally, it also focuses on current technologies used to characterize those microbial inhabitants and recommendations for further research.

12.
Chaos ; 32(12): 123125, 2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-36587326

RESUMEN

A natural circulation system (NCS) has a broad application in the sector of thermal engineering, for example, in nuclear reactors due to its capability in transferring heat without any support of external power or a mechanical device. NCSs, although designed for steady operation, have been found to exhibit dynamical behavior, such as periodic oscillations, depending on the input heater power. The heater power, otherwise assumed to be steady, can be fluctuating in practice. The present study focuses on the dynamics of a single-phase square NCS, which exhibits periodic dynamics and is subjected to an external harmonic perturbation (chosen as the simplest form of fluctuation) over the steady heater power. The objective of the study is to study the dynamics of NCS under external (harmonic) disturbances using the framework of forced synchronization. Toward that, a 1D transient model of a square-shaped NCS is simulated with harmonically forced input power. The transition in the nature of synchronization between mass flux oscillations and the external forcing has been characterized by varying the frequency and amplitude of external perturbation independently. We find different nonlinear effects of the harmonic forcing, such as exhibition of quasiperiodic dynamics, frequency pulling/pushing, and frequency locking or forced synchronization. The aforementioned characterization techniques open up an avenue for detailed analysis of the more complex type of fluctuating input heat in real systems.

13.
Mol Cell Biol ; 42(1): e0034421, 2022 01 20.
Artículo en Inglés | MEDLINE | ID: mdl-34780285

RESUMEN

Although a large number of recent studies indicate strong association of FKBP5 (aka FKBP51) functions with various stress-related psychiatric disorders, the overall mechanisms are poorly understood. Beyond a few studies indicating its functions in regulating glucocorticoid receptor, and AKT signaling pathways, other functional roles (if any) are unclear. Here, we report an antiproliferative role of human FKBP5 through negative regulation of expression of proliferation-related genes. Mechanistically, we show that, owing to the same region of interaction on cyclin-dependent kinse 9 (CDK9), human FKBP5 directly competes with cyclin T1 for functional positive transcription elongation factor b (P-TEFb) complex formation. In vitro biochemical assays, coupled with cell-based assays, showed a strong negative effect of FKBP5 on P-TEFb-mediated phosphorylation of diverse substrates. Consistently, FKBP5 knockdown showed enhanced P-TEFb complex formation that led to increased global RNA polymerase II C-terminal domain (CTD) phosphorylation, expression of proliferation-related genes, and subsequent proliferation. Thus, our results show an important role for FKBP5 in negative regulation of P-TEFb functions within mammalian cells.


Asunto(s)
Factor B de Elongación Transcripcional Positiva/metabolismo , Proteínas de Unión a Tacrolimus/metabolismo , Transcripción Genética/genética , Ciclina T/metabolismo , Quinasa 9 Dependiente de la Ciclina/metabolismo , Ciclinas/genética , Humanos , Proteínas Serina-Treonina Quinasas/metabolismo , ARN Polimerasa II/metabolismo
14.
Chin J Traumatol ; 25(3): 161-165, 2022 May.
Artículo en Inglés | MEDLINE | ID: mdl-34794857

RESUMEN

PURPOSE: The COVID-19 pandemic has caused 1.4 million deaths globally and is associated with a 3-4 times increase in 30-day mortality after a fragility hip fracture with concurrent COVID-19 infection. Typically, death from COVID-19 infection occurs between 15 and 22 days after the onset of symptoms, but this period can extend up to 8 weeks. This study aimed to assess the impact of concurrent COVID-19 infection on 120-day mortality after a fragility hip fracture. METHODS: A multi-centre prospective study across 10 hospitals treating 8% of the annual burden of hip fractures in England between 1st March and 30th April, 2020 was performed. Patients whose surgical treatment was payable through the National Health Service Best Practice Tariff mechanism for "fragility hip fractures" were included in the study. Patients' 120-day mortality was assessed relative to their peri-operative COVID-19 status. Statistical analysis was performed using SPSS version 27. RESULTS: A total of 746 patients were included in this study, of which 87 (11.7%) were COVID-19 positive. Mortality rates at 30- and 120-day were significantly higher for COVID-19 positive patients relative to COVID-19 negative patients (p < 0.001). However, mortality rates between 31 and 120-day were not significantly different (p = 0.107), 16.1% and 9.4% respectively for COVID-19 positive and negative patients, odds ratio 1.855 (95% CI 0.865-3.978). CONCLUSION: Hip fracture patients with concurrent COVID-19 infection, provided that they are alive at day-31 after injury, have no significant difference in 120-day mortality. Despite the growing awareness and concern of "long-COVID" and its widespread prevalence, this does not appear to increase medium-term mortality rates after a hip fracture.


Asunto(s)
COVID-19 , Fracturas de Cadera , Fracturas de Cadera/cirugía , Humanos , Pandemias , Estudios Prospectivos , Estudios Retrospectivos , Medicina Estatal , Reino Unido/epidemiología
15.
Chem Sci ; 12(44): 14863-14870, 2021 Nov 17.
Artículo en Inglés | MEDLINE | ID: mdl-34820102

RESUMEN

A direct Pd(ii)-catalyzed kinetic resolution of heteroaryl-enabled sulfoximines through an ortho-C-H alkenylation/arylation of arenes has been developed. The coordination of the sulfoximine pyridyl-motif and the chiral amino acid MPAA ligand to the Pd(ii)-catalyst controls the enantio-discriminating C(aryl)-H activation. This method provides access to a wide range of enantiomerically enriched unreacted aryl-pyridyl-sulfoximine precursors and C(aryl)-H alkenylation/arylation products in good yields with high enantioselectivity (up to >99% ee), and selectivity factor up to >200. The coordination preference of the directing group, ligand effect, geometry constraints, and the transient six-membered concerted-metalation-deprotonation species dictate the stereoselectivity; DFT studies validate this hypothesis.

16.
Chem Commun (Camb) ; 57(67): 8280-8283, 2021 Aug 28.
Artículo en Inglés | MEDLINE | ID: mdl-34319322

RESUMEN

A rhodium-catalysed direct formylmethylation adopting vinylene carbonate as an ethynol equivalent is reported. The developed catalytic system is further utilised for the oxidant-free production of esters with the liberation of hydrogen gas. Some control experiments are conducted to elucidate the reaction mechanism.

17.
Environ Toxicol Pharmacol ; 87: 103717, 2021 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-34314872

RESUMEN

This study assessed some important physiological biomarkers of freshwater edible fish Cyprinus carpio following exposure to 10 % (T1) and 20 % (T2) sublethal concentrations of Alpha-cypermethrin (A-cyp) over a total period of 45 days. Behavioral responses were noticed and Kaplan-Meier survival curves were prepared during acute toxicity study. Total serum protein concentration, total erythrocyte count, hemoglobin, packed cell volume, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and total leukocytes count were decreased significantly (p < 0.05), while the blood glucose, total serum lipid concentration, and clotting time were increased significantly (p < 0.05) over control. The most affected fish group and most significantly altered biomarker under toxic stress of A-cyp were identified using integrated biomarker response (IBR). The biomarker response index (BRI) values measured the overall health status of the treated fish and indicated that moderate adverse effects were exerted on the fish group exposed to T2 for 45 days.


Asunto(s)
Carpas , Insecticidas/toxicidad , Piretrinas/toxicidad , Contaminantes Químicos del Agua/toxicidad , Animales , Conducta Animal/efectos de los fármacos , Biomarcadores/sangre , Carpas/sangre , Carpas/fisiología , Pruebas Hematológicas , Hemoglobinas/análisis , Dosificación Letal Mediana
18.
Chem Rec ; 20(9): 1017-1042, 2020 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-32779389

RESUMEN

Multiple C-H bond functionalizations promptly install diverse groups on the molecular framework and consequently fabricate complex molecular entities. This review briefly surveys the conceptual development of directing group assisted unsymmetrical multiple functionalization of arene C(sp2 )-H bonds, which is exceedingly appealing and highly important.

19.
Org Lett ; 22(14): 5706-5711, 2020 07 17.
Artículo en Inglés | MEDLINE | ID: mdl-32638595

RESUMEN

Transition-metal-catalyzed activation of inert C-H bonds and subsequent C-C bond formation have emerged as powerful synthetic tools for the synthesis of elaborate cyclic molecules. In this report, we introduce an efficient synthetic method of 3,4-unsubstituted isocoumarins adopting an electron-deficient CpERh complex as the catalyst. The use of vinylene carbonate as a vinylene transfer reagent enables the direct construction of isocoumarins from readily available benzoic acids, without any external oxidants as well as bases. The reaction mechanism is evaluated by computational analysis to find an unprecedented "rhodium shift" event within the catalytic cycle.

20.
J Org Chem ; 85(13): 8618-8626, 2020 Jul 02.
Artículo en Inglés | MEDLINE | ID: mdl-32519873

RESUMEN

An unprecedented ruthenium (Ru)-catalyzed twofold unsymmetrical annulation of 3-O/N-allyl benzoic acid derivatives with isocyanates for the construction of dihydro-furan/indole-fused phthalimide scaffolds is discussed. This double-unsymmetrical functionalization of both o,o'-C-H bonds of arene moiety is explicitly viable under the influence of methylphenyl sulfoximine directing group constructing three different [C-C/C-C(O)/N-C(O)] bonds under a single catalytic system. A broad scope with all six-carbon-substituted arene motifs, control experiments, and gram-scale synthesis make the synthetic model viable and significant.

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