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The construction of multiple continuous fully substituted carbon centers, which serve as unique structural motif in natural products, is a challenging topic in organic synthesis. Herein, we report a hydrated [3+2] cyclotelomerization of butafulvenes to create contiguous fully substituted carbon backbone. In the presence of scandium triflate, all‐carbon skeleton with spiro fused tricyclic ring can be constructed in high diastereoselectivity by utilizing butafulvene as the synthon. Mechanistic studies suggest that this atom‐economic reaction probably proceeds through a synergistic process containing butafulvenes dimerization and nucleophilic attack by water. In addition, the tricyclic product can undergo a series of synthetic derivatizations, which highlights the potential applications of this strategy. The recyclability of Sc(OTf)3 has also been demonstrated to show its robust performance in this hydrated cyclotelomerization. [ABSTRACT FROM AUTHOR]

Bridged benzazepine scaffolds, possessing unique structural and physicochemical activities, are widespread in various natural products and drugs. The construction of these skeletons often requires elaborate synthetic effort with low efficiency. Herein, we develop a simple and divergent approach for constructing various bridged benzazepines by a photocatalytic intermolecular dearomatization of naphthalene derivatives with readily available α‐amino acids. The bridged motif is created via a cascade sequence involving photocatalytic 1,4‐hydroaminoalkylation, alkene isomerization and cyclization. Interestingly, the diastereoselectivity can be regulated through different reaction modes in the cyclization step. Moreover, aminohydroxylation and its further bromination have also been demonstrated to access highly functionalized bridged benzazepines. Preliminary mechanistic studies have been performed to get insights into the mechanism. This method provides a divergent synthetic approach for construction of highly functionalized bridged benzazepines, which have been otherwise difficult to access. [ABSTRACT FROM AUTHOR]

In this work, we systematically investigate the photocatalytic mechanism of g-C3N4/BiOI (001) through hybrid functional calculations based on first-principles theory. The staggered band structure is observed in the g-C3N4/BiOI (001); meanwhile, a built-in electric field exists from the g-C3N4 monolayer to the BiOI surface at the interface. BiOI has lower band edges, which bend downward at the interface; whereas g-C3N4 has higher band edges, which bend upward. With Coulomb interaction and the built-in electric field, photo-generated electrons in the conduction bands (CB) of BiOI recombine with photo-generated holes in the valence bands (VB) of g-C3N4. Meanwhile, the stronger reduction capacity for photo-excited electrons in the g-C3N4's CB and the stronger oxidation capacity for photo-generated holes in the BiOI (001)'s VB are retained. Therefore, a direct Z-scheme heterostructure character is presented. As a result, the electrons and holes generated by the photons can be separated and migrate highly effectively at the interface. The separated electrons and holes can effectively participate in the redox reactions with water/pollutants to produce the photocatalytically reactive species superoxide ions (˙O2−) and hydroxyl radicals (˙OH), respectively. This is consistent with the experimental results. It is also worth noting that the g-C3N4/BiOI (001) heterostructure shows a larger difference in the effective mass of carriers. Therefore, the direct Z-scheme charge transfer and separation mechanism and the larger effective mass difference of carriers lead to the superior photocatalytic activity of the g-C3N4/BiOI (001) in experiments. A few speculations and controversies that arose from the experiments are clarified. [ABSTRACT FROM AUTHOR]

Study concerning the clinical features, electrocardiogram (ECG) findings and outcomes in patients presenting with acute total occlusion of left main coronary artery (LM) without collateral circulation is limited. 25 patients with acute total LM occlusion without collateral circulation by emergency coronary angiography, from muti-center registry, were retrospectively studied. The clinical and angiographic characteristics, ECG and in-hospital mortality were reviewed. Nineteen patients (76%) presented with cardiogenic shock. Twelve (60%, 12/20) patients had coronary slow flow or no reflow phenomenon after primary percutaneous coronary intervention (PCI). The in-hospital mortality rate was 88% (n = 22). All the patients presented with ST-segment elevation myocardial ischemia (STEMI) pattern, mostly involving leads I, aVL, V2, V3, V4, V5 and ST-segment depression in leads II, III and aVF. Acute total LM occlusion without collateral circulation portends high in-hospital mortality. Anterior ST elevation in the precordial leads from V2 to V4 through V6, and ST elevation in leads I and aVL, accompanying with ST depression in the inferior leads is associated with acute total LM occlusion without collateral circulation. [ABSTRACT FROM AUTHOR]

A high-voltage zero-voltage-zero-current-switched dc-dc converter with low voltage stress is presented in this paper. Its circuit structure is extended from a previously developed zero-voltage-switched dc-dc converter consisting of six series-connected switching devices, one three-phase transformer, and an output current tripler. The voltage stress on each switching device is only one-third of the input voltage. Compared with the previous converter, apart from retaining the advantage of having low voltage stresses on the switches, the main advancements of the proposed converter have also included 1) wider soft-switching range; 2) elimination of circulating energy on the primary side during the freewheeling stage; and 3) use of phase-shift pulsewidth modulation in output voltage control. Detailed topological operations and steady-state characteristics of the converter will be given. A 2.2-kW, 990-V/110-V dc-dc converter prototype has been built and tested. Experimental results are favorably compared with the theoretical predictions. Index Terms--DC-DC conversion, high-voltage converter, soft-switching converters.