scholarly journals Aminoalkyl radicals as halogen-atom transfer agents for activation of alkyl and aryl halides

Science ◽  
2020 ◽  
Vol 367 (6481) ◽  
pp. 1021-1026 ◽  
Author(s):  
Timothée Constantin ◽  
Margherita Zanini ◽  
Alessio Regni ◽  
Nadeem S. Sheikh ◽  
Fabio Juliá ◽  
...  
Keyword(s):  
Halogen Atom ◽  
Building Blocks ◽  
Aryl Halides ◽  
Atom Transfer ◽  
Reduction Potentials ◽  
Tributyltin Hydride ◽  
Organic Halides ◽  
Wide Range ◽  
Carbon Carbon Bonds ◽  
Radical Processes

Organic halides are important building blocks in synthesis, but their use in (photo)redox chemistry is limited by their low reduction potentials. Halogen-atom transfer remains the most reliable approach to exploit these substrates in radical processes despite its requirement for hazardous reagents and initiators such as tributyltin hydride. In this study, we demonstrate that α-aminoalkyl radicals, easily accessible from simple amines, promote the homolytic activation of carbon-halogen bonds with a reactivity profile mirroring that of classical tin radicals. This strategy conveniently engages alkyl and aryl halides in a wide range of redox transformations to construct sp3-sp3, sp3-sp2, and sp2-sp2 carbon-carbon bonds under mild conditions with high chemoselectivity.

Application of α-Amino Radicals as the Reaction Activators

Synthesis ◽  
2021 ◽  
Author(s):  
Yong-liang Su ◽  
Michael P. Doyle
Keyword(s):  
Halogen Atom ◽  
Building Blocks ◽  
Short Review ◽  
Single Electron ◽  
Radical Species ◽  
Sulfonium Salts ◽  
Radical Intermediates ◽  
Organic Halides

α-Aminoalkyl radicals are easily accessible through multiple pathways from various precursors. Apart from their utilization as N-containing building blocks, they have recently been used as halogen atom abstraction reagents or single-electron reductants to transform organic halides or sulfonium salts to their corresponding highly reactive radical species. Benefiting from the richness of various halides and the diverse reactivity of radical intermediates, new transformations of halides and sulfonium salts have been developed. This short review summarizes this emerging chemistry that uses α-amino radicals as the reaction activators.

Proposal for halogen atom transfer mechanism for Ullmann O-arylation of phenols with aryl halides

2012 ◽  
Vol 41 (45) ◽  
pp. 13832 ◽  
Author(s):  
Songlin Zhang ◽  
Zhenzhong Zhu ◽  
Yuqiang Ding
Keyword(s):  
Halogen Atom ◽  
Transfer Mechanism ◽  
Aryl Halides ◽  
Atom Transfer

scholarly journals Transition Metal Catalyzed Azidation Reactions

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1173
Author(s):  
Roberto Sala ◽  
Camilla Loro ◽  
Francesca Foschi ◽  
Gianluigi Broggini
Keyword(s):  
Transition Metal ◽  
Materials Science ◽  
Building Blocks ◽  
Organic Azides ◽  
Wide Range ◽  
Carbon Carbon Bonds ◽  
Transition Metal Catalyzed ◽  
Vinyl Azides ◽  
Catalyzed Reactions ◽  
Metal Catalyzed

A wide range of methodologies for the preparation of organic azides has been reported in the literature for many decades, due to their interest as building blocks for different transformations and their applications in biology as well as in materials science. More recently, with the spread of the use of transition metal-catalyzed reactions, new perspectives have also materialized in azidation processes, especially concerning the azidation of C–H bonds and direct difunctionalization of multiple carbon-carbon bonds. In this review, special emphasis will be placed on reactions involving substrates bearing a leaving group, hydroazidation reactions and azidation reactions that proceed with the formation of more than one bond. Further reactions for the preparation of allyl and vinyl azides as well as for azidations involving the opening of a ring complete the classification of the material.

Photo-induced 1,2-carbohalofunctionalization of C–C multiple bonds via ATRA pathway

2020 ◽  
Vol 18 (41) ◽  
pp. 8278-8293 ◽  
Author(s):  
Debojyoti Bag ◽  
Harpreet Kour ◽  
Sanghapal D. Sawant
Keyword(s):  
Efficient Method ◽  
Building Blocks ◽  
Atom Transfer ◽  
Atom Economy ◽  
Multiple Bonds ◽  
Radical Processes

Carbohalofunctionalization of C–C multiple bonds via atom transfer radical processes constitutes an efficient method for the construction of halogenated building blocks with complete atom economy. This review summarizes the recent advancements.

Factors Affecting Molecular Self-Assembly and Its Mechanism

2012 ◽  
Vol 9 (1) ◽  
pp. 43 ◽  
Author(s):  
Hueyling Tan
Keyword(s):  
Self Assembly ◽  
Building Blocks ◽  
Molecular Engineering ◽  
Molecular Structures ◽  
Polymer Science ◽  
New Approach ◽  
Factors Affecting ◽  
Dna Structures ◽  
Self Assembling ◽  
Wide Range

Molecular self-assembly is ubiquitous in nature and has emerged as a new approach to produce new materials in chemistry, engineering, nanotechnology, polymer science and materials. Molecular self-assembly has been attracting increasing interest from the scientific community in recent years due to its importance in understanding biology and a variety of diseases at the molecular level. In the last few years, considerable advances have been made in the use ofpeptides as building blocks to produce biological materials for wide range of applications, including fabricating novel supra-molecular structures and scaffolding for tissue repair. The study ofbiological self-assembly systems represents a significant advancement in molecular engineering and is a rapidly growing scientific and engineering field that crosses the boundaries ofexisting disciplines. Many self-assembling systems are rangefrom bi- andtri-block copolymers to DNA structures as well as simple and complex proteins andpeptides. The ultimate goal is to harness molecular self-assembly such that design andcontrol ofbottom-up processes is achieved thereby enabling exploitation of structures developed at the meso- and macro-scopic scale for the purposes oflife and non-life science applications. Such aspirations can be achievedthrough understanding thefundamental principles behind the selforganisation and self-synthesis processes exhibited by biological systems.

Stereospecific, Palladium-catalyzed C(sp3)–H Alkenylation and Alkynylation of a Proline Derivative Enabled by 8-Aminoquinoline as a Directing Group

2020 ◽  
Author(s):  
Aleksandra Balliu ◽  
Aaltje Roelofje Femmigje Strijker ◽  
Michael Oschmann ◽  
Monireh Pourghasemi Lati ◽  
Oscar Verho
Keyword(s):  
Carboxylic Acid ◽  
Building Blocks ◽  
Wide Range ◽  
Palladium Catalyzed ◽  
Directing Group ◽  
High Yields ◽  
Vinyl Iodides ◽  
Initial Results

<p>In this preprint, we present our initial results concerning a stereospecific Pd-catalyzed protocol for the C3 alkenylation and alkynylation of a proline derivative carrying the well utilized 8‑aminoquinoline directing group. Efficient C–H alkenylation was achieved with a wide range of vinyl iodides bearing different aliphatic, aromatic and heteroaromatic substituents, to furnish the corresponding C3 alkenylated products in good to high yields. In addition, we were able show that this protocol can also be used to install an alkynyl group into the pyrrolidine scaffold, when a TIPS-protected alkynyl bromide was used as the reaction partner. Furthermore, two different methods for the removal of the 8-aminoquinoline auxiliary are reported, which can enable access to both <i>cis</i>- and <i>trans</i>-configured carboxylic acid building blocks from the C–H alkenylation products.</p>

Efficient Prediction of Structural and Electronic Properties of Hybrid 2D Materials Using DFT and Machine Learning

2018 ◽  
Author(s):  
Sherif Tawfik ◽  
Olexandr Isayev ◽  
Catherine Stampfl ◽  
Joseph Shapter ◽  
David Winkler ◽  
...  
Keyword(s):  
Machine Learning ◽  
Band Gap ◽  
Density Functional ◽  
2D Materials ◽  
Van Der Waals ◽  
Building Blocks ◽  
Machine Learning Techniques ◽  
Interlayer Distance ◽  
Computational Screening ◽  
Wide Range

Materials constructed from different van der Waals two-dimensional (2D) heterostructures offer a wide range of benefits, but these systems have been little studied because of their experimental and computational complextiy, and because of the very large number of possible combinations of 2D building blocks. The simulation of the interface between two different 2D materials is computationally challenging due to the lattice mismatch problem, which sometimes necessitates the creation of very large simulation cells for performing density-functional theory (DFT) calculations. Here we use a combination of DFT, linear regression and machine learning techniques in order to rapidly determine the interlayer distance between two different 2D heterostructures that are stacked in a bilayer heterostructure, as well as the band gap of the bilayer. Our work provides an excellent proof of concept by quickly and accurately predicting a structural property (the interlayer distance) and an electronic property (the band gap) for a large number of hybrid 2D materials. This work paves the way for rapid computational screening of the vast parameter space of van der Waals heterostructures to identify new hybrid materials with useful and interesting properties.

Application of Nitrogen Heterocyclic Carbenes in Organocatalysis

2020 ◽  
Vol 09 ◽  
Author(s):  
Minita Ojha ◽  
R. K. Bansal
Keyword(s):  
Asymmetric Catalysis ◽  
Building Blocks ◽  
Structural Features ◽  
Heterocyclic Carbenes ◽  
Stetter Reaction ◽  
Metal Pollutants ◽  
Synthetic Strategy ◽  
Wide Range ◽  
Benzoin Condensation ◽  
Nitrogen Heterocyclic

Background: During the last two decades, horizon of research in the field of Nitrogen Heterocyclic Carbenes (NHC) has widened remarkably. NHCs have emerged as ubiquitous species having applications in a broad range of fields, including organocatalysis and organometallic chemistry. The NHC-induced non-asymmetric catalysis has turned out to be a really fruitful area of research in recent years. Methods: By manipulating structural features and selecting appropriate substituent groups, it has been possible to control the kinetic and thermodynamic stability of a wide range of NHCs, which can be tolerant to a variety of functional groups and can be used under mild conditions. NHCs are produced by different methods, such as deprotonation of Nalkylhetrocyclic salt, transmetallation, decarboxylation and electrochemical reduction. Results: The NHCs have been used successfully as catalysts for a wide range of reactions making a large number of building blocks and other useful compounds accessible. Some of these reactions are: benzoin condensation, Stetter reaction, Michael reaction, esterification, activation of esters, activation of isocyanides, polymerization, different cycloaddition reactions, isomerization, etc. The present review includes all these examples published during the last 10 years, i.e. from 2010 till date. Conclusion: The NHCs have emerged as versatile and powerful organocatalysts in synthetic organic chemistry. They provide the synthetic strategy which does not burden the environment with metal pollutants and thus fit in the Green Chemistry.

scholarly journals MXenes for future nanophotonic device applications

Nanophotonics ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 1831-1853
Author(s):  
Jaeho Jeon ◽  
Yajie Yang ◽  
Haeju Choi ◽  
Jin-Hong Park ◽  
Byoung Hun Lee ◽  
...  
Keyword(s):  
Solar Cells ◽  
Transition Metal ◽  
Wide Spectrum ◽  
Building Blocks ◽  
Optoelectronic Device ◽  
High Yield ◽  
Saturable Absorption ◽  
Nanophotonic Device ◽  
Wide Range ◽  
Device Applications

AbstractTwo-dimensional (2D) layers of transition metal carbides, nitrides, or carbonitrides, collectively referred to as MXenes, are considered as the new family of 2D materials for the development of functional building blocks for optoelectronic and photonic device applications. Their advantages are based on their unique and tunable electronic and optical properties, which depend on the modulation of transition metal elements or surface functional groups. In this paper, we have presented a comprehensive review of MXenes to suggest an insightful perspective on future nanophotonic and optoelectronic device applications based on advanced synthesis processes and theoretically predicted or experimentally verified material properties. Recently developed optoelectronic and photonic devices, such as photodetectors, solar cells, fiber lasers, and light-emitting diodes are summarized in this review. Wide-spectrum photodetection with high photoresponsivity, high-yield solar cells, and effective saturable absorption were achieved by exploiting different MXenes. Further, the great potential of MXenes as an electrode material is predicted with a controllable work function in a wide range (1.6–8 eV) and high conductivity (~104 S/cm), and their potential as active channel material by generating a tunable energy bandgap is likewise shown. MXene can provide new functional building blocks for future generation nanophotonic device applications.

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