Ring (chemistry)
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The “Cyclopropyl Fragment” is a Versatile Player that Frequently Appears in Preclinical/Clinical Drug Molecules Open
Recently, there has been an increasing use of the cyclopropyl ring in drug development to transition drug candidates from the preclinical to clinical stage. Important features of the cyclopropane ring are, the (1) coplanarity of the three …
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Recent Methodologies That Exploit C–C Single-Bond Cleavage of Strained Ring Systems by Transition Metal Complexes Open
In this review, synthetic and mechanistic aspects of key methodologies that exploit C-C single-bond cleavage of strained ring systems are highlighted. The focus is on transition-metal-catalyzed processes that are triggered by C-C bond acti…
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From Chemical Topology to Molecular Machines (Nobel Lecture) Open
To a large extent, the field of “molecular machines” started after several groups were able to prepare, reasonably easily, interlocking ring compounds (named catenanes for compounds consisting of interlocking rings and rotaxanes for rings …
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Roads, Railroads, and Decentralization of Chinese Cities Open
We investigate how urban railroad and highway configurations have influenced urban form in Chinese cities since 1990. Each radial highway displaces 4% of central city population to surrounding regions, and ring roads displace about an addi…
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N-Heterocyclic Carbene Complexes in C–H Activation Reactions Open
In this contribution, we provide a comprehensive overview of C-H activation methods promoted by NHC-transition metal complexes, covering the literature since 2002 (the year of the first report on metal-NHC-catalyzed C-H activation) through…
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Bioisosteres of the Phenyl Ring: Recent Strategic Applications in Lead Optimization and Drug Design Open
The benzene moiety is the most prevalent ring system in marketed drugs, underscoring its historic popularity in drug design either as a pharmacophore or as a scaffold that projects pharmacophoric elements. However, introspective analyses o…
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Heterocycles in Medicinal Chemistry Open
Heteroatoms constitute a very common fragment of a number of active pharmaceutical ingredients as well as excipients; from the point of view of significance, it is all the same if these are isosterically/bioisosterically replaced carbons/c…
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Quest for Novel Chemical Entities through Incorporation of Silicon in Drug Scaffolds Open
In order to optimize a lead molecule for further development, bioisosteric replacements are generally adopted as one of the strategies. Silicon appears to be the right choice as a carbon isostere because of the similarity in chemical prope…
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Catalytic Enantioselective Ring-Opening Reactions of Cyclopropanes Open
This review describes the development of enantioselective methods for the ring opening of cyclopropanes. Both approaches based on the reaction of nonchiral cyclopropanes and (dynamic) kinetic resolutions and asymmetric transformations of c…
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“Cut and Sew” Transformations via Transition-Metal-Catalyzed Carbon–Carbon Bond Activation Open
The transition metal-catalyzed "cut and sew" transformation has recently emerged as a useful strategy for preparing complex molecular structures. After oxidative addition of a transition metal into a carbon-carbon bond, the resulting two c…
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Two-dimensional polyaniline (C <sub>3</sub> N) from carbonized organic single crystals in solid state Open
Significance Two-dimensional (2D) polyaniline (PANI) has been realized for the first time, to our knowledge, by direct solid-state reaction of organic single crystals. The 2D PANI framework consists of six nitrogen atoms that periodically …
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Semisimple Subalgebras of Semisimple Lie Algebras Open
Let g be a Lie algebra. The subalgebra classification problem is to create a list of all subalgebras of g up to equivalence. The purpose of this thesis is to provide a software toolkit within the Differential Geometry package of Maple for …
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Breaking Amides using Nickel Catalysis Open
Amides have been widely studied for decades, but their synthetic utility has remained limited in reactions that proceed with rupture of the amide C-N bond. Using Ni catalysis, we have found that amides can now be strategically employed in …
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Oxetanes: Recent Advances in Synthesis, Reactivity, and Medicinal Chemistry Open
The four-membered oxetane ring has been increasingly exploited for its contrasting behaviors: its influence on physicochemical properties as a stable motif in medicinal chemistry and its propensity to undergo ring-opening reactions as a sy…
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The RING 2.0 web server for high quality residue interaction networks Open
Residue interaction networks (RINs) are an alternative way of representing protein structures where nodes are residues and arcs physico-chemical interactions. RINs have been extensively and successfully used for analysing mutation effects,…
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Transition-Metal-Catalyzed C–H Bond Activation for the Formation of C–C Bonds in Complex Molecules Open
Site-predictable and chemoselective C-H bond functionalization reactions offer synthetically powerful strategies for the step-economic diversification of both feedstock and fine chemicals. Many transition-metal-catalyzed methods have emerg…
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Radical Ring-Opening Polymerization: Scope, Limitations, and Application to (Bio)Degradable Materials Open
Cyclic monomers bearing either vinyl or exomethylene groups have the ability to be polymerized through a radical pathway via a ring-opening mechanism (addition-fragmentation process), leading to the introduction of functionalities in the p…
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<i>AceDRG</i>: a stereochemical description generator for ligands Open
The program AceDRG is designed for the derivation of stereochemical information about small molecules. It uses local chemical and topological environment-based atom typing to derive and organize bond lengths and angles from a small-molecul…
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Tuning Azoheteroarene Photoswitch Performance through Heteroaryl Design Open
Photoswitchable compounds, which can be reversibly switched between two isomers by light, continue to attract significant attention for a wide array of applications. Azoheteroarenes represent a relatively new but understudied type of photo…
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Recent Advances in the Enantioselective Synthesis of Chiral Amines via Transition Metal-Catalyzed Asymmetric Hydrogenation Open
Chiral amines are key structural motifs present in a wide variety of natural products, drugs, and other biologically active compounds. During the past decade, significant advances have been made with respect to the enantioselective synthes…
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Put a ring on it: application of small aliphatic rings in medicinal chemistry Open
Aliphatic small rings including cyclopropanes, cyclobutanes, oxetanes, azetidines and bicyclo[1.1.1]pentanes have been increasingly exploited in medicinal chemistry. This review summarises judicious successful application and reported limi…
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Heteroatom-Doped Nanographenes with Structural Precision Open
Nanographenes, which are defined as nanoscale (1-100 nm) graphene cutouts, include quasi-one-dimensional graphene nanoribbons (GNRs) and quasi-zero-dimensional graphene quantum dots (GQDs). Polycyclic aromatic hydrocarbons (PAHs) larger th…
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Rings in Clinical Trials and Drugs: Present and Future Open
We present a comprehensive analysis of all ring systems (both heterocyclic and nonheterocyclic) in clinical trial compounds and FDA-approved drugs. We show 67% of small molecules in clinical trials comprise only ring systems found in marke…
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Metal-Free Thiophene-Sulfur Covalent Organic Frameworks: Precise and Controllable Synthesis of Catalytic Active Sites for Oxygen Reduction Open
Defective or heteroatom-doped metal-free carbon materials (MFCMs) have been regarded as efficient oxygen reduction reaction (ORR) catalysts in the past decade. However, the active centers for ORR in MFCMs are hard to confirm precisely and …
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The Necessary Nitrogen Atom: A Versatile High-Impact Design Element for Multiparameter Optimization Open
There is a continued desire in biomedical research to reduce the number and duration of design cycles required to optimize lead compounds into high-quality chemical probes or safe and efficacious drug candidates. The insightful application…
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Femtosecond x-ray spectroscopy of an electrocyclic ring-opening reaction Open
X-ray vision catches Woodward-Hoffmann The celebrated Woodward-Hoffmann (W-H) rules rationalize a variety of rapid bond rearrangements in organic molecules. The key insight involved symmetry conservation in the electronic journey from reac…
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Molecular architecture of the inner ring scaffold of the human nuclear pore complex Open
Blueprint for a macromolecular machine Nuclear pore complexes (NPCs) consist of around 1000 protein subunits, are embedded in the membrane that surrounds the nucleus, and regulate transport between the nucleus and the cytoplasm. Although t…
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Strain-Release Heteroatom Functionalization: Development, Scope, and Stereospecificity Open
Driven by the ever-increasing pace of drug discovery and the need to push the boundaries of unexplored chemical space, medicinal chemists are routinely turning to unusual strained bioisosteres such as bicyclo[1.1.1]pentane, azetidine, and …
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Ring Confidential Transactions Open
This article introduces a method of hiding transaction amounts in the strongly decentralized anonymous cryptocurrency Monero. Similar to Bitcoin, Monero is a cryptocurrency which is distributed through a proof-of-work “mining” process havi…
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Origami‐Based Reconfigurable Metamaterials for Tunable Chirality Open
Origami is the art of folding two‐dimensional (2D) materials, such as a flat sheet of paper, into complex and elaborate three‐dimensional (3D) objects. This study reports origami‐based metamaterials whose electromagnetic responses are dyna…