scholarly journals Quantifying and understanding the steric properties of N-heterocyclic carbenes

2017 ◽  
Vol 53 (18) ◽  
pp. 2650-2660 ◽  
Author(s):  
Adrián Gómez-Suárez ◽  
David J. Nelson ◽  
Steven P. Nolan
Keyword(s):  
Heterocyclic Carbenes ◽  
Feature Article

This Feature Article presents and discusses the use of different methods to quantify and explore the steric impact of N-heterocyclic carbene (NHC) ligands.

scholarly journals Polar organometallic strategies for regioselective C–H metallation of N-heterocyclic carbenes

2018 ◽  
Vol 54 (20) ◽  
pp. 2455-2462 ◽  
Author(s):  
Marina Uzelac ◽  
Eva Hevia
Keyword(s):  
Heterocyclic Carbenes ◽  
Feature Article ◽  
Recent Emergence

This Feature Article focuses on the recent emergence of s-block metal-mediated N-heterocyclic carbene metallations and the new opportunities this methodology offers to access unique anionic NHC fragments.

Redox- and light-switchable N-heterocyclic carbenes: a “soup-to-nuts” course on contemporary structure–activity relationships

2019 ◽  
Vol 55 (31) ◽  
pp. 4451-4466 ◽  
Author(s):  
Yeonkyeong Ryu ◽  
Guillermo Ahumada ◽  
Christopher W. Bielawski
Keyword(s):  
Heterocyclic Carbenes ◽  
Feature Article ◽  
Structure Activity Relationships ◽  
Structure Activity

This Feature Article offers in-depth, design-to-application discussions of redox-switchable N-heterocyclic carbenes that have been field tested.

Reactivity of Grubbs–Hoveyda II Complexes Including Extended N-Heterocyclic Carbenes with a Bicyclic Camphor-Based Framework

Synthesis ◽  
2017 ◽  
Vol 49 (13) ◽  
pp. 2852-2864 ◽  
Author(s):  
René Wilhelm ◽  
Eduard Rais ◽  
Ulrich Flörke
Keyword(s):  
High Activity ◽  
Olefin Metathesis ◽  
Heterocyclic Carbenes ◽  
Short Route ◽  
Feature Article ◽  
Metathesis Reactions

This feature article discusses the synthesis of new asymmetric Grubbs–Hoveyda II complexes with extended N-heterocyclic carbenes containing a bicyclic camphor-based framework. The new enantiopure complexes can be prepared in a short route from the chiral pool. The extended carbene-based catalyst shows high activity in olefin metathesis reactions. The new complexes exhibited enantioselectivity in an asymmetric ROCM desymmetrization. Depending on the substituents on the nitrogen atoms of the carbenes, the opposite enantiomer was formed in excess.

Feature Article: Design of Porous Polymeric Materials from Miscellaneous Macromolecular Architectures: An Overview

Polymer News ◽  
2004 ◽  
Vol 29 (7) ◽  
pp. 205-212 ◽  
Author(s):  
Rengarajan Balaji ◽  
Sylvie Boileau ◽  
Philippe Guérin ◽  
Daniel Grande
Keyword(s):  
Polymeric Materials ◽  
Feature Article

Aryl-substituted Triarsiranes: Synthesis and Reactivity

2020 ◽  
Author(s):  
André Schumann ◽  
Jonas Bresien ◽  
Malte Fischer ◽  
Christian Hering-Junghans
Keyword(s):  
Organic Chemistry ◽  
Electronic Structure ◽  
Heterocyclic Carbenes ◽  
Synthetic Approaches ◽  
Inorganic And Organic

Cyclotriarsanes are rare and limited synthetic approaches have hampered reactivity studies on these systems. Described in here is a scalable synthetic protocol towards (AsAr)<sub>3</sub> (Ar = Dip, 2,6-<sup>i</sup>Pr<sub>2</sub>-C<sub>6</sub>H<sub>3</sub>; Tip, 2,4,6-<sup>i</sup>Pr<sub>3</sub>-C<sub>6</sub>H<sub>2</sub>), which allowed to study their reactivity towards [Cp<sub>2</sub>Ti(C<sub>2</sub>(SiMe<sub>3</sub>)<sub>2</sub>], affording titanocene diarsene complexes and towards N-heterocyclic carbenes (NHCs) to give straightforward access to a variety of NHC-arsinidene adducts. The electronic structure of the titanium diarsene complxes has been studied and they are best described as Ti(IV) species with a doubly reduced As<sub>2</sub>Ar<sub>2</sub> ligand. These findings will make (AsAr)<sub>3</sub> valuable precursors in the synthetic inorganic and organic chemistry.

Foreign Investment Dilemma: Real Estate on Jeju Island, Korea Gregory Chu 01/31/19 Volume 61 Photo Essay Moving Cuba Jenny Pettit, Charles O. Collins 12/14/18 Feature Article Igarka Vanishes: The Story of a Rapidly Shrinking Russian Arctic City Kelsey Nyland, Valery Grebenets, Nikolay Shiklomanov, Dmitry Streletskiy 10/26/18 Geo Quiz Quiz Nine: Energy Wesley Reisser 09/03/18 Feature Article Agricultural Social Networks as the future of Karst Science Communication in Phong Nha-Kẻ Bàng National Park, Vietnam Elizabeth Willenbrink, Leslie North, Vu Thi Minh Nguyet 08/06/18 Photo Essay Guyana's Linden to Lethem Road: A Metaphor for Conservation and Development Karen Barton 07/05/18 Photo Essay Schools in South Korea: Where have All the Children Gone? Michael Robinson 06/03/18 Geo Quiz Quiz Eight: The Geography of Food Origins Antoinette WinklerPrins 05/10/18 Feature Article America's Public Lands: What, Where, Why, and What Next? David J. Rutherford 04/22/18 Feature Article Cuba's Precarious Population Pyramid Charles O. Collins 03/19/18 Feature Article Reimagining Zimbabwe’s Cape-to-Cairo Railroad Thomas Wikle 02/21/18 Geo Quiz Quiz Seven: The Built Environment Deborah Popper 02/05/18 Photo Essay Constructing Nationalism Through the Cityscape: The Skopje 2014 Project Wesley Reisser 01/24/18 Feature Article Agave Cultivation, Terracing, and Conservation in Mexico Matthew LaFevor, Jordan Cissell, James Misfeldt 01/17/18 Volume 60 Geo Quiz Quiz Six: Symbols Wesley Reisser 12/22/17 Photo Essay Organic Agriculture, Scale, and the Production of a Region in Northeast, India David Meek 12/08/17 Feature Article The Joola: The Geographical Dimensions of Africa's Greatest Shipwreck Karen Barton 11/02/17 Geo Quiz Quiz Five: Transportation Wesley Reisser 09/30/17 Feature Article Shrinking Space and Expanding Population: Socioeconomic Impacts of Majuli’s Changing Geography Avijit Sahay, Nikhil Roy 09/07/17 Photo Essay A Stroll through Seville W. George Lovell 08/14/17 Geo Quiz Quiz Four: Water Wesley Reisser 06/22/17 Photo Essay Wildlife Conservation in Kenya and Tanzania and Effects on Maasai Communities Daniel Sambu 05/24/17 Feature Article Floods Collide with Sprawl in Louisiana's Amite River Basin Craig Colten 04/24/17 Geo Quiz Quiz Three: The Arctic Wesley Reisser 03/08/17 Feature Article Exploring Arctic Diversity by Hitting the Road: Where Finland, Norway, and Russia Meet Julia Gerlach, Nadir Kinossian 02/06/17 Photo Essay Urban Agriculture in Helsinki, Finland Sophia E. Hagolani-Albov 01/03/17 Volume 59 Feature Article Living and Spirtual Worlds of Mali's Dogon People Thomas Wikle 10/27/16 Photo Essay Postcards from Oaxaca's Past and Present Scott Brady 10/27/16 Geo Quiz Quiz Two: Sustainability and Conservation Wesley Reisser 10/27/16 Feature Article From Ranching to Fishing – the Cultural Landscape of the Northern Pacific Coast of Baja California, Mexico Antoinette WinklerPrins, Pablo Alvarez, Gerardo Bocco, Ileana Espejel 07/06/16 Photo Essay Many Destinations, One Place Called Home: Migration and Livelihood for Rural Bolivians Marie Price 07/06/16 Geo Quiz Quiz One: Explorers Wesley Reisser 07/06/16 Foreign Investment Dilemma: Real Estate on Jeju Island, Korea

2019 ◽  
Vol 62 ◽  
Author(s):  
Gregory H. Chu
Keyword(s):  
Real Estate ◽  
Foreign Investment ◽  
Science Communication ◽  
Cultural Landscape ◽  
Wildlife Conservation ◽  
Northeast India ◽  
Jeju Island ◽  
The Arctic ◽  
Feature Article ◽  
Photo Essay

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.

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