Publications by authors named "C-H Loh"

Purpose: The purpose of this study was to evaluate the risk of newly diagnosed retinal vein occlusion (RVO) in patients with type 2 diabetes (T2D) using sodium-glucose cotransporter-2 inhibitors (SGLT-2i) compared to dipeptidyl peptidase-4 inhibitors (DPP-4i).

Methods: Claims data from the National Health Insurance Research Database of Taiwan were used in this nationwide retrospective cohort study. A target trial emulation framework was applied.

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The selective oxidation of benzylic C-H bonds is a pivotal transformation in organic synthesis. Undoubtedly, achieving efficient and highly selective aerobic oxidation of methylarenes to benzaldehydes has been highly challenging due to the propensity of benzaldehyde to undergo overoxidation under typical aerobic conditions. Herein, we propose an innovative approach to address this issue by leveraging electrocatalytic processes, facilitated by ion-pair mediators [PhC][B(CF)].

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Background: The double burden of malnutrition, described as the coexistence of malnutrition and obesity, is a growing global health issue. This study examines the combined effects of obesity and malnutrition on patients with acute myocardial infarction (AMI).

Methods: Patients presenting with AMI to a percutaneous coronary intervention-capable hospital in Singapore between January 2014 and March 2021 were retrospectively studied.

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A transition-metal-free strategy regarding an iodine-sodium percarbonate catalysis to achieve the -aminomethylation of phenols in aqueous media has been developed. This method can effectively broaden a wide range of phenols, tolerate sensitive functional groups, and achieve the late-stage functionalization of ten functional molecules that contain phenolic structures.

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Background: L-type Ca1.2 calcium channel, the primary gateway for Ca influx in smooth muscles, is widely regulated by multiple posttranslational modifications, such as protein kinase-mediated phosphorylation and nitric oxide-induced S-nitrosylation. However, the effect of S-nitrosylation on Ca1.

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Alkenes and their derivatives are featured widely in a variety of natural products, pharmaceuticals, and advanced materials. Significant efforts have been made toward the development of new and practical methods to access this important class of compounds by selectively activating the alkenyl C(sp)-H bonds in recent years. In this comprehensive review, we describe the state-of-the-art strategies for the direct functionalization of alkenyl sp C-H and C-F bonds until June 2022.

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Background: Evidence about the association between types of oral anticoagulants and hazards of diabetes complications is limited in patients with atrial fibrillation (AF) and diabetes mellitus (DM).

Objective: To compare the hazards of diabetes complications and mortality between patients with AF and DM receiving non-vitamin K antagonist oral anticoagulants (NOACs) and those receiving warfarin.

Design: A retrospective cohort study.

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With the increasing awareness of sustainable chemistry principles, the development of an efficient and mild strategy for C(sp)-H bond activation of nitrogen-containing compounds without the utilization of any oxidant and metal is still highly desired and challenging. Herein, we present a metal-free reaction system that enables C-H bond functionalization of aliphatic sulfonamides using DABCO as a promoter under mild conditions, affording a series of α,β-unsaturated imines in good yields with high selectivities. This protocol tolerates a broad range of functionalities and can serve as a powerful synthetic tool for the late-stage modification of complex compounds.

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Herein, we disclose a transition-metal-free reaction system that enables α-cyanation of sulfonamides through C-H bond cleavage for the preparation of α-amino nitriles, including difficult-to-access all-alkyl α-tertiary scaffolds. More than 50 substrate examples prove a wide functional group tolerance. Additionally, its synthetic practicality is highlighted by gram-scalability and the late-stage modification of natural compounds.

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Site-specific incorporation of deuterium into drug molecules to study and improve their biological properties is crucial for drug discovery and development. Herein, we describe a palladium-catalyzed room-temperature deuterogenolysis of carbon-oxygen bonds in alcohols and ketones with D balloon for practical synthesis of deuterated pharmaceuticals and chemicals with benzyl-site (sp C-H) D-incorporation. The highlights of this deoxygenative deuteration strategy are mild conditions, broad scope, practicability and high chemoselectivity.

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Reported herein is a practical method for macrolactam synthesis via a Rh(III)-catalyzed ring closing alkene-alkene cross-coupling reaction. The reaction proceeded via a Rh-catalyzed alkenyl sp C-H activation process, which allows access to macrocyclic molecules of different ring sizes. Macrolactams containing a conjugated diene framework could be easily prepared in high chemoselectivities and , stereoselectivities.

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A simple and practical method to access N-substituted 2-pyridones via a formal [3+3] annulation of enaminones with acrylates based on RhIII-catalyzed C-H functionalization was developed. Control and deuterated experiments led to a plausible mechanism involving C-H bond cross-coupling and aminolysis cyclization. This strategy provides a short synthesis of structural motifs of N-substituted 2-pyridones.

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This paper reports a highly site-selective alkylation of heteroarene -oxides using hypervalent iodine(III) carboxylates to serve as an alkylating agent in the presence of a cheap copper catalyst under visible light conditions. This mild method proceeds at room temperature in an air atmosphere and can withstand various heteroarene -oxides as well as various primary, secondary, and tertiary alkyl carboxylic acids. It also provides a practical method for enabling the rapid conversion of commercially available raw materials into medically relevant "drug-like" molecules.

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Background: Heart failure (HF) is the most common long-term complication of acute myocardial infarction (MI). Understanding plasma proteins associated with post-MI HF and their gene expression may identify new candidates for biomarker and drug target discovery.

Methods: We used aptamer-based affinity-capture plasma proteomics to measure 1305 plasma proteins at 1 month post-MI in a New Zealand cohort (CDCS [Coronary Disease Cohort Study]) including 181 patients post-MI who were subsequently hospitalized for HF in comparison with 250 patients post-MI who remained event free over a median follow-up of 4.

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We report a chelation-assisted C-H arylation of various indoles with sterically and electronically diverse (hetero)arylsilanes enabled by cost-effective Cp*-free cobalt catalysis. Key to the success of this strategy is the judicious choice of copper(II) fluoride as a bifunctional sliane activator and catalyst reoxidant. This methodology features a broad substrate scope and good functional group compatibility.

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Background: Frailty is the pre-eminent exigency of aging. Although frailty-related impairments are preventable, and multidomain interventions appear more effective than unimodal ones, the optimal components remain uncertain.

Methods: We devised multidomain interventions against physical and cognitive decline among prefrail/frail community-dwelling ≥65-year-olds and evaluated these in complementary cluster-randomized trials of efficacy and participant empowerment.

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We have presented a unique example of dehydrogenative acylation of enamides with aldehydes enabled by an earth-abundant iron catalyst. The protocol provides the straightforward access to valuable β-ketoenamides with ample substrate scope and excellent functional group tolerance. Notably, distinct C-H acylation of enamide rather than at N-H moiety site occurs with absolute -selectivity was observed.

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Ruthenium-catalyzed heteroannulation between enamides and isocyanates has been realized as a complementary approach to conventional strategies for the synthesis of pyrimidin-4-ones. High step- and atom-economy was achieved for the rapid construction of such privileged scaffolds, which are found in a multitude of pharmaceutical compounds. The generality and practicability of this transformation were reflected by the broad scope of substrates with diverse functional groups, large-scale synthesis, and late-stage diversification.

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A nondirected amidation reaction of aromatic C-H bond was developed under iron(II) catalysis, using sulfonyl azides as the nitrogen source. The reaction displayed a broad substrate scope and good regioselectivities in the aspects of aromatic ring vs alkyl chain and different aromatic position of (alkyl)arenes. This method provided a new protocol for the synthesis of some aromatic amines, which were hard to achieve in a previous report.

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An efficient cobalt-catalyzed ring-opening reaction of bench-stable 1,2-oxazetidines with heteroarenes was unprecedentedly developed. The sustainable Cp *Co(III) catalyst enables a distinctive merger of C-H activation with concomitant N-O and C-C cleavages of 1,2-oxazetidine, leading to site-selective C-H aminomethylation and hydroxymethylation of heteroaromatic compounds containing a broad range of functional groups. Preliminary control experiments unravel some essential mechanistic features of this one-pot transformation.

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An efficient tertiary alkylation reaction of olefins with 1,3-dicarbonyl compounds was developed by virtue of copper catalyst without the use of expensive ligands or additives. In contrast to alkyl Heck-type reaction, alkyl halide is not required. Notably, by varying the nitrogen and air atmosphere, the reaction selectively produces alkylation and alkylation-oxygenation products, respectively.

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Background: Internal jugular venous catheterization is performed for numerous therapeutic interventions. Although ultrasound-guided internal jugular venous catheterization is the gold standard for this procedure, complications can still occur. Various scanning axes, namely, the short axis (SA), long axis (LA), and oblique axis (OA), have been developed to ameliorate these complications.

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An expedient [5 + 1] annulation method via Rh(III)-catalyzed C-H bond functionalization of enaminones to synthesize polyaromatic rings is described. The reaction tolerates a broad range of functional groups and offers a new entry to construct polycyclic aromatic compounds with amino and formyl substituents. A possible reaction mechanism was proposed based on the results obtained from isotope labeling experiments.

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Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL; --like ALL) in children with National Cancer Institute (NCI) intermediate- or high-risk (HR) ALL is associated with poor outcome. Ph-like ALL is characterized by genetic alterations that activate cytokine receptor and kinase signaling and may be amenable to treatment with tyrosine kinase inhibitors. The prevalence, outcome, and potential for targeted therapy of Ph-like ALL in standard-risk (SR) ALL is less clear.

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