Synthesis of Allenes by Hydroalkylation of 1,3-Enynes with Ketones Enabled by Cooperative Catalysis.

A method for the synthesis of allenes by the addition of ketones to 1,3-enynes by cooperative Pd(0)Senphos/B(C6F5)3/NR3 catalysis is described. A wide range of aryl- and aliphatic ketones undergo addition to various 1,3-enynes in high yields at room temperature. Mechanistic investigations revealed a rate-determining outer-sphere proton transfer mechanism, which was corroborated by DFT calculations.

trans-Hydroalkynylation of Internal 1,3-Enynes Enabled by Cooperative Catalysis.

A cooperative catalyst system involving a Pd(0)/Senphos complex, tris(pentafluorophenyl)borane, copper bromide, and an amine base, is demonstrated to catalyze trans-hydroalkynylation of internal 1,3-enynes. For the first time, a Lewis acid catalyst is shown to promote the reaction involving the emerging outer-sphere oxidative reaction step. The resulting cross-conjugated dieneynes are versatile synthons for organic synthesis, and their characterization reveals distinct photophysical properties depending on the positioning of the donor/acceptor substituents along the conjugation path.

A syn outer-sphere oxidative addition: the reaction mechanism in Pd/Senphos-catalyzed carboboration of 1,3-enynes.

We report a combined experimental and computational study of Pd/Senphos-catalyzed carboboration of 1,3-enynes utilizing DFT calculations, 31P NMR study, kinetic study, Hammett analysis and Arrhenius/Eyring analysis. Our mechanistic study provides evidence against the conventional inner-sphere ß-migratory insertion mechanism. Instead, a syn outer-sphere oxidative addition mechanism featuring a Pd-π-allyl intermediate followed by coordination-assisted rearrangements is consistent with all the experimental observations.

Coupled improvements on hydrodynamics and water quality by flowing water in towns with lakes.

With the worsening environmental problems in the plain river network, flowing water has become important because of its obvious improvement effect. In order to solve water quality and water mobility problems of the river network in Shengze Town, this paper establishes four flowing water scenarios and compares the associated improvements in water quality and hydrodynamics of the river network with the use of coupled hydrodynamic and water quality models. It is identified as the best scenario to dispatch 20 m3/s of water from the Xiegang River downstream of the Qingxi River and 20 m3/s of water from Lake Xiangjiadang to Lake Beiyandang. Results of this scenario show a significant improvement in the water mobility of the river network in the southern area of the Qingxi River, with the flow rate increasing by 38.23%. The water quality in Lake Beiyandang has upgraded from Class V to Class IV (based on the Chinese water quality standards), and the water quality downstream of the Qingxi River has improved a lot. Findings in this work could provide references for the development of flowing water scenarios in similar watersheds.

Mechanism of Pd/Senphos-Catalyzed trans-Hydroboration of 1,3-Enynes: Experimental and Computational Evidence in Support of the Unusual Outer-Sphere Oxidative Addition Pathway.

The reaction mechanism of the Pd/Senphos-catalyzed trans-hydroboration reaction of 1,3-enynes was investigated using various experimental techniques, including deuterium and double crossover labeling experiments, X-ray crystallographic characterization of model reaction intermediates, and reaction progress kinetic analysis. Our experimental data are in support of an unusual outer-sphere oxidative addition mechanism where the catecholborane serves as a suitable electrophile to activate the Pd0-bound 1,3-enyne substrate to form a Pd-η3-π-allyl species, which has been determined to be the likely resting state of the catalytic cycle. Double crossover labeling of the catecholborane points toward a second role played by the borane as a hydride delivery shuttle. Density functional theory calculations reveal that the rate-limiting transition state of the reaction is the hydride abstraction by the catecholborane shuttle, which is consistent with the experimentally determined rate law: rate = k[enyne]0[borane]1[catalyst]1. The computed activation free energy ΔG‡ = 17.7 kcal/mol and KIE (kH/kD = 1.3) are also in line with experimental observations. Overall, this work experimentally establishes Lewis acids such as catecholborane as viable electrophilic activators to engage in an outer-sphere oxidative addition reaction and points toward this underutilized mechanism as a general approach to activate unsaturated substrates.

C-Boron Enolates Enable Palladium Catalyzed Carboboration of Internal 1,3-Enynes.

A new family of carbon-bound boron enolates, generated by a kinetically controlled halogen exchange between chlorocatecholborane and silylketene acetals, is described. These C-boron enolates are demonstrated to activate 1,3-enyne substrates in the presence of a Pd0 /Senphos ligand complex, resulting in the first examples of a carboboration reaction of an alkyne with enolate-equivalent nucleophiles. Highly substituted dienyl boron building blocks are produced in excellent site-, regio-, and diastereoselectivity by the described catalytic cis-carboboration reaction.

Application of ultrasound combined with enhanced MRI by Gd-BOPTA in diagnosing hepatocellular carcinoma.

OBJECTIVE: This study aimed to probe into the diagnostic level and clinical value of ultrasound combined with enhanced MRI by Gd-BOPTA in hepatocellular carcinoma (HCC). METHODS: A total of 58 suspected HCC patients in our hospital from January 2016 to November 2020 were collected as the research subjects, including 37 HCC and 21 non-HCC patients. The diagnostic results of ultrasound and enhanced MRI by Gd-BOPTA were compared, and the microvascular invasion in patients was assessed. The independent risk factors of microvascular invasion were analyzed by logistics regression, and the diagnostic value of these factors was tested by ROC. RESULTS: The specificity, sensitivity and accuracy of enhanced MRI by Gd-BOPTA were 89.19%, 90.48% and 94.59%, respectively. The specificity, sensitivity and accuracy of ultrasound were 85.71%, 72.97% and 91.89%, and those of combined diagnosis were 76.19%, 97.30%, and 89.66%, respectively. The confirmation rate of microvascular invasion of enhanced MRI by Gd-BOPTA was dramatically higher than with ultrasound. Tumor diameter, comorbid cirrhosis and differentiation degree were independent risk factors of microvascular invasion, and ROC curve revealed that the area under the curve (AUC) of these risk factors was > 0.6. CONCLUSION: Enhanced MRI by Gd-BOPTA combined with ultrasound has good diagnostic value in HCC patients, and it can be widely used in early HCC diagnosis and clinical examination.

Evaluation of the value of the VI-RADS scoring system in assessing muscle infiltration by bladder cancer.

BACKGROUND: The Vesical Imaging-Reporting and Data System (VI-RADS) was created in 2018, and a 5-point VI-RADS scoring system was proposed to determine whether the muscularis of the bladder has been infiltrated by tumor tissues. PURPOSE: To verify the accuracy of the VI-RADS scoring system in predicting muscle-invasive bladder cancer and to explore its value in clinical application. MATERIALS AND METHODS: A total of 220 patients with bladder cancer who underwent multiparameter magnetic resonance imaging from January 2017 to June 2019 were selected. Then, two radiologists with equivalent qualifications gave their diagnoses of bladder tumors on T2-weighted imaging, diffusion-weighted imaging and dynamic contrast enhanced imaging. Meanwhile, the bladder tumor was also scored on the basis of the VI-RADS system; for multifocal tumors, the highest tumor load was selected for scoring. Furthermore, the final pathological results of the patients were unknown during the imaging diagnosis and scoring. Next, the VI-RADS score was compared with the pathological results after surgery, and the ability of the VI-RADS score to assess the degree of muscularis infiltration was finally analyzed. RESULTS: A total of 220 patients were included in our study, including 194 males and 26 females. Among them, the pathological results were 113 cases of muscle-invasive bladder cancer and 107 cases of non-muscle-invasive bladder cancer. The results showed that there was a positive correlation between the pathological results and VI-RADS score (r = 0.821, P < 0.05). The area under the receiver operating characteristic curve of the VI-RADS score was 0.960 (95% CI: 0.937, 0.983). When the VI-RADS score was above 3, the sensitivity, specificity and accuracy of predicting muscle-invasive bladder cancer were 82.3, 95.3 and 88.64%, respectively. CONCLUSION: The VI-RADS scoring system has good diagnostic value in predicting the degree of tumor invasion and can be used to guide clinical decision-making and management.

Polarization-switchable and wavelength-controllable multi-functional metasurface for focusing and surface-plasmon-polariton wave excitation.

Realizing versatile functionalities in a single photonic device is crucial for photonic integration. We here propose a polarization-switchable and wavelength-controllable multi-functional metasurface. By changing the polarization state of incident light, its functionality can be switched between the flat focusing lens and exciting surface-plasmon-polariton (SPP) wave. Interestingly, by tuning the wavelength of incident light, the generated SPP waves can also be controlled at desired interfaces, traveling along the upper or lower interface of the metasurface, or along both of them, depending on whether the incident light satisfies the first or second Kerker condition. This polarization-switchable and wavelength-controllable multifunctional metasurface may provide flexibility in designing tunable or multifunctional metasurfaces and may find potential applications in highly integrated photonic systems.