Publications by authors named "C-H Song"

A ruthenium-catalyzed oxidative coupling of 2-aryl-quinazolinones with olefins via C-H bond activation followed by an intramolecular aza-Michael reaction is described. This strategy allows the direct and efficient construction of pyrrolo[2,1-b]quinazolin-9(1H)-one scaffolds.

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Upon single-crystal-to-single-crystal (SCSC) oxidation/reduction, reversible structural transformations take place between the anionic porous zeolite-like Cu(I) framework and a topologically equivalent neutral Cu(I)Cu(II) mixed-valent framework. The unique conversion behavior of the Cu(I) framework endowed it as a redox-switchable catalyst for the direct arylation of heterocycle C-H bonds.

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An efficient approach to 3-alkynylpyrroles has been developed through the gold-catalyzed reaction of β-enamino derivatives with terminal alkynes, which features complete regiocontrol, relatively wide substrate scope, and high functional group tolerance. Mechanistic studies show that the reaction proceeds through the gold-catalyzed cascade oxidative C-H/C-H cross-coupling, cyclization and alkynylation.

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Purpose: To investigate the cardiac computed tomographic (CT) findings and clinical implications of subprosthetic pannus in patients who have undergone aortic valve replacement.

Materials And Methods: The institutional review board approved this retrospective study, and the need to obtain written informed consent was waived. From April 2011 to March 2012, 88 patients (mean age, 63 years; 45 men) with a prosthetic aortic valve who underwent cardiac CT were retrospectively selected.

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The catalytic C-H addition of pyridines to allenes has been achieved for the first time by using a half-sandwich scandium catalyst, thus constituting a straightforward and atom-economical route for the synthesis of alkenylated pyridine derivatives. The reaction proceeded regio- and stereoselectively, affording a new family of alkenylated pyridine compounds which are otherwise difficult to synthesize. A cationic Sc-η(2) -pyridyl species was isolated and confirmed to be a key catalyst species in this transformation.

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The possibility of developing new methods for the efficient construction of organic molecules via disconnections other than traditional functional group transformations has driven the interest in direct functionalization of C-H bonds. The ubiquity of C-H bonds makes such transformations attractive, but they also pose several challenges. The first is the reactivity and selectivity of C-H bonds.

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This study aims to determine the appropriate microclimate cooling systems (MCSs) to reduce heat stress and improve human performance of occupational workers and their practicality in the occupational field. Meta-analysis was employed to summarize, analyze, and compare the effects of various MCSs on human performance with corresponding physiological and psychological responses, thereby providing solid suggestions for selecting suitable MCSs for occupational workers. Wearing MCSs significantly attenuated the increases in core temperature (-0.

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Here we report a new and mild Rh(III)-catalyzed and alcohol-involved carbenoid C-H insertion into N-phenoxyacetamides using α-diazomalonates. This reaction provided a straightforward way for installing both an α-quaternary carbon center and a free-OH moiety into the phenyl ring, thus giving access to useful 2-(2-hydroxyphenyl)-2-alkoxymalonates with good substrate/functional group tolerance.

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Purpose: To compare radiofrequency (RF) ablation with nonanatomic resection (NAR) as first-line treatment in patients with a single Barcelona Clinic Liver Cancer (BCLC) stage 0 or A hepatocellular carcinoma (HCC) and to evaluate the long-term outcomes of both therapies.

Materials And Methods: This retrospective study was approved by the institutional review board. The requirement for informed consent was waived.

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We report herein an efficient Pd-catalyzed direct C-H bond functionalization of heteroarenes via an isocyanide insertion strategy for the synthesis of di-(hetero)aryl ketones and di-(hetero)aryl alkylamines. The methodology involves a three component reaction between an azole, a haloarene and an isocyanide resulting in the formation of an imine, which in turn is either hydrolyzed or reduced to get the desired product.

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Herein we disclose the first example of Rh(iii)-catalyzed intermolecular annulation of indoles with terminal alkynes to give highly efficient one-pot access to privileged carbazoles. The mild reaction features moderate to good yields, exclusive regioselectivity, broad substrate scope, and excellent functional group tolerance.

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Tandem multi-site cyclization triggered by Rh(iii)-catalyzed C-H activation has been achieved for highly efficient synthesis of spirocycle indolin-3-one (C2-cyclization), benzo[a]carbazole (C3-cyclization) and an unusual indoxyl core (N1-cyclization). In particular, the synthesis of pseudo-indoxyl is typically completed within 10 min, and the reaction tolerates air, water and a range of solvents.

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Purpose: To compare the long-term outcomes of repeated hepatic resection and radiofrequency (RF) ablation for recurrent hepatocellular carcinoma (HCC) by using propensity score matching.

Materials And Methods: This retrospective study was approved by the institutional review board, and the requirement to obtain informed consent was waived. Thirty-nine patients who underwent repeated hepatic resection and 178 who underwent RF ablation for recurrent HCC (mean tumor size ± standard deviation, 1.

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Based on the well-defined five-membered aryl gold(iii) complexes, [Au(tpy)X] ( and ) and [AuBr(Ph)(tpy)] (), as well as the aryl gold(iii) complex [AuCl(Ph)(tpy)] () (tpy = 2-(-tolyl)pyridine) as reliable models, we present a detailed study of the mechanism for gold(iii)-catalyzed oxidative cross-coupling reactions between cycloaurable arenes and arylboronic acids. Here we report the direct evidence for a mechanistic proposal including arene C-H activation, transmetallation and biaryl reductive elimination. The chelation-assisted C-H activation strategy has been used for the development of the gold(iii)-catalyzed C-H bond arylation of arenes with aryl reagents to forge extended π-conjugated systems.

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A new strategy is reported for the economical synthesis of indoles bearing an N-(3-aminobut-2-enoyl) substituent through Rh(III)-catalyzed redox-neutral C-H activation of pyrazolones and alkynes. This approach utilizes cheap substrates and mild reaction conditions to access a unique class of indoles via a N-N bond oxidative cleavage without loss of the N-terminus, therefore meeting all the atom/step/redox economy principles.

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Background Aims: Rheumatoid arthritis is a systemic autoimmune disorder. In this study, we first compared the therapeutic effects of syngeneic and xenogeneic adipose tissue-derived stem cells on a collagen-induced arthritis mouse model. Second, we investigated the synergistic preventive effects of CTLA4Ig and adipose tissue-derived mesenchymal stromal cells (ASCs) as a therapeutic substance.

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A novel iron-catalyzed aerobic oxidative reaction to synthesize disubstituted isoxazoles from homopropargylic alcohol, t-BuONO, and H2O is developed. The method provides mild conditions to afford a variety of useful substituted heterocycles in an efficient and regioselective manner. The mechanism has been studied and proposed, which indicates that the transformation can be realized through construction of a C═N bond and C═O bond, C-H oxidation, and then cyclization.

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Here a new, mild and versatile method for one-pot cascade synthesis of diverse N-methoxyisoquinolinediones via Rh(III)-catalyzed regioselective carbenoid insertion C-H activation/cyclization of N-methoxybenzamides with α-diazotized Meldrum's acid has been achieved. Extension of the developed Rh(III) catalysis for building new analogs of the marketed drug Edaravone has also been demonstrated.

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An efficient rhodium(III)-catalyzed tandem three-component reaction of imines, alkynes and aldehydes through CH activation has been developed. High stereo- and regioselectivity, as well as good yields were obtained in most cases. The simple and atom-economical approach offers a broad scope of substrates, providing polycyclic skeletons with potential biological properties.

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Palladium(II)-catalyzed dual C-H functionalization of indoles with cyclic diaryliodoniums was successfully achieved, providing a concise method to synthesize dibenzocarbazoles. In a single operation, two C-C bonds and one ring were formed. The reaction was ligand free and tolerated air and moisture conditions.

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Highly effective CuCl-mediated C-H alkoxylation of arenes and heteroarenes has been developed by using a 2-aminopyridine 1-oxide moiety as an N,O-bidentate directing group. The reaction proceeds smoothly using a broad range of substrates to afford o-alkoxylated benzoic and heteroaromatic amide products. Moreover, the reaction system shows remarkable compatibility when hexafluoroisopropanol is used as a coupling parter; halogen, nitro, ether, alkoxy, ester, and sulfonyl functional groups are all tolerated.

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Mitral valve prolapse (MVP), the most frequent cause of severe nonischemic mitral regurgitation, often warrants surgical or interventional valve repair. The severity of mitral regurgitation positively correlates with the development of heart failure and death. Even in patients who are asymptomatic, severe mitral regurgitation causes higher rates of death, heart failure, and atrial fibrillation.

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p-Toluenesulfonohydrazide (PTSH) was shown to promote the highly efficient direct arylation of unactivated arenes with aryl iodides, bromides, or chlorides in the presence of potassium tert-butoxide without the assistance of any transition metals. The reaction proceeds through base-promoted homolytic aromatic substitution (BHAS) involving aryl radicals and arylradical anions as intermediates.

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The room-temperature oxidative C-H/C-H cross-couplings between (hetero)arenes and alkenes, coumarins or quinones have been reported by using a highly electrophilic palladium species [Pd(TFA)2], generated in situ from Pd(OAc)2 and TFA, as the catalyst and cheap (NH4)2S2O8 as the oxidant under air.

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An intermolecular C-H functionalization method is developed for the synthesis of 3-hydroxy-2-oxindoles. Rh(III)-catalyzed N-nitroso-directed C-H addition to ethyl 2-oxoacetate allows subsequent denitrosation-triggered cyclization construction of 3-hydroxy-2-oxindoles. The method features a broad substrate scope and its synthetic utility is demonstrated on the synthesis of target compounds bearing functional groups (hydroxyl, bromo) amenable to further elaboration.

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