Oxidation of pyrrole-2-carboxylates with o-chloranil and its synthetic application

金沢大学理工研究域物質化学系t-Butyl 3,4-dialkyl-1H-pyrrole-2-carboxylates were oxidized with ochloranil in the presence of MeOH to afford the corresponding 5-methoxypyrrolin-2-one derivatives. The resulting 5-methoxypyrrolin-2-one was reacted with various nucleophiles under acidic conditions to afford the functionalized pyrrolinone derivatives in good yields. © The Japan Institute of Heterocyclic Chemistry

Direct oxidation of 4-methylpyrrole-2-carboxylates with DDQ in the presence of a glycol

Oxidation of 4-methylpyrrole-2-carboxylates with DDQ in the presence of a glycol proceeded smoothly on the methyl group at the C4 position regioselectively to afford the corresponding pyrrole-2,4-dicarboxylates directly. Direct oxidation of a methyl group of 2,4,6-trimethylphenol and 3-methyl-9H-carbazole into carboxylates was also demonstrated. © 2012 The Japan Institute of Heterocyclic Chemistry

Follow-up of true visceral artery aneurysm after coil embolization by three-dimensional contrast-enhanced MR angiography

PURPOSE:We aimed to evaluate the outcomes of coil embolization of true visceral artery aneurysms by three-dimensional contrast-enhanced magnetic resonance (MR) angiography. MATERIALS AND METHODS:We used three-dimensional contrast-enhanced MR angiography, which included source images, to evaluate 23 patients (mean age, 60 years; range, 28–83 years) with true visceral artery aneurysms (splenic, n=15; hepatic, n=2; gastroduodenal, n=2; celiac, n=2; pancreaticoduodenal, n=1; gastroepiploic, n=1) who underwent coil embolization. Angiographic aneurysmal occlusion was revealed in all cases. Follow-up MR angiography was conducted with either a 1.5 or 3 Tesla system 3–25 months (mean, 18 months) after embolization. MR angiography was evaluated for aneurysmal occlusion, hemodynamic status, and complications. RESULTS:Complete aneurysmal occlusion was determined in 22 patients (96%) on follow-up MR angiography (mean follow-up period, 18 months). Neck recanalization, which was observed at nine and 20 months after embolization, was confirmed in one of eight patients (13%) using a neck preservation technique. In this patient, a small neck recanalization covered by a coil mass was demonstrated. The complete hemodynamic status after embolization was determined in 21 patients (91%); the visualization of several collateral vessels, such as short gastric arteries, after parent artery occlusion was poor compared with that seen on digital subtraction angiography in the remaining two patients (9%). An asymptomatic localized splenic infarction was confirmed in one patient (4%). CONCLUSION:Our study presents the follow-up results from three-dimensional contrast-enhanced MR angiography, which confirmed neck recanalization, the approximate hemodynamic status, and complications. This effective and less invasive method may be suitable for serial follow-up after coil embolization of true visceral aneurysms

Management of visceral artery embolization using 0.010-inch detachable microcoils

Transcatheter coil embolization is used primarily to treat arterial hemorrhages, tumors, aneurysms, and vascular malformations. However, conventional microcatheter systems cannot always be employed in difficult cases. In this technical note, we describe how small-diameter primary coils and microcatheter tips that are thinner than normal can be used to increase the safety and reliability of coil embolization

Assessment of Bi-Ventricular and Bi-Atrial Areas Using Four-Chamber Cine Cardiovascular Magnetic Resonance Imaging: Fully Automated Segmentation with a U-Net Convolutional Neural Network

Four-chamber (4CH) cine cardiovascular magnetic resonance imaging (CMR) facilitates simultaneous evaluation of cardiac chambers; however, manual segmentation is time-consuming and subjective in practice. We evaluated deep learning based on a U-Net convolutional neural network (CNN) for fully automated segmentation of the four cardiac chambers using 4CH cine CMR. Cine CMR datasets from patients were randomly assigned for training (1400 images from 70 patients), validation (600 images from 30 patients), and testing (1000 images from 50 patients). We validated manual and automated segmentation based on the U-Net CNN using the dice similarity coefficient (DSC) and Spearman’s rank correlation coefficient (ρ); p < 0.05 was statistically significant. The overall median DSC showed high similarity (0.89). Automated segmentation correlated strongly with manual segmentation in all chambers—the left and right ventricles, and the left and right atria (end-diastolic area: ρ = 0.88, 0.76, 0.92, and 0.87; end-systolic area: ρ = 0.81, 0.81, 0.92, and 0.83, respectively; p < 0.01). The area under the curve for the left ventricle, left atrium, right ventricle, and right atrium showed high scores (0.96, 0.99, 0.88, and 0.96, respectively). Fully automated segmentation could facilitate simultaneous evaluation and detection of enlargement of the four cardiac chambers without any time-consuming analysis

New Isolable Dialkylsilylene and Its Isolable Dimer That Equilibrate in Solution

The new isolable dialkylsilylene <b>3</b> bearing a bidentate alkyl substituent was synthesized. Recrystallization of silylene <b>3</b> gave yellow crystals of <b>3</b> and orange-red crystals of tetraalkyldisilene <b>4</b>, a dimer of <b>3</b>. In the solid state, <b>3</b> exists as a monomer with a closest distance of 6.745 Å between dicoordinate silicon atoms, while disilene <b>4</b> has a remarkably long SiSi double bond distance of 2.252 Å. An equilibrium between <b>3</b> and <b>4</b> in solution was observed by NMR and UV–vis spectroscopies, and the thermodynamic parameters of the equilibrium were estimated to be Δ<i>H</i> = −36 ± 3 kJ mol^–1 and Δ<i>S</i> = −170 ± 15 J mol^–1 K^–1. Analysis of the percent buried volume, a measure of the steric demand around the divalent silicon, showed that the flexible steric bulkiness of the alkyl substituent of <b>3</b> and <b>4</b> allows the reversible dimerization of silylene <b>3</b> to disilene <b>4</b> and the isolation of both species