The successful isolation and characterization of an N-heterocyclic carbene in 1991 opened up a new class of organic compounds for investigation. From these beginnings as academic curiosities, N-heterocyclic carbenes today rank among the most powerful tools in organic chemistry, with numerous applications in commercially important processes. Here we provide a concise overview of N-heterocyclic carbenes in modern chemistry, summarizing their general properties and uses and highlighting how these features are being exploited in a selection of pioneering recent studies.

An overview of N-heterocyclic carbenes

The fascinating story of olefin (or alkene) metathesis (eq
1) began almost five decades ago, when Anderson and
Merckling reported the first carbon-carbon double-bond
rearrangement reaction in the titanium-catalyzed polymerization of norbornene. Nine years later, Banks and Bailey reported “a new disproportionation reaction . . . in which olefins are converted to homologues of shorter and longer carbon chains...”. In 1967, Calderon and co-workers named this metal-catalyzed redistribution of carbon-carbon double bonds olefin metathesis, from the Greek word “μeτάθeση”, which means change of position. These contributions have since served as the foundation for an amazing research field, and olefin metathesis currently represents a powerful transformation in chemical synthesis, attracting a vast amount of interest both in industry and academia.

https://core.ac.uk/download/pdf/4884240.pdf

Ruthenium-based heterocyclic carbene-coordinated olefin metathesis catalysts.

We gratefully acknowledge funding and support from King Abdullah University of Science and Technology (KAUST). Thanks are also due to the KAUST communication department for designing several images for this Review.

Magnetically recoverable nanocatalysts.

Organocatalytic Reactions Enabled by N-Heterocyclic Carbenes.

Molecular separation with organic solvent nanofiltration: a critical review.

Herein, we report the synthesis and characterization of four novel fullerene C60 derivatives. The carbon cage of these C60 derivatives is decorated with one or two dodecyl or triethylene glycol tails, through the appropriately modified ortho-xyleno bridge, by utilizing the Diels-Alder reaction of C60 with the corresponding especially designed, novel, in situ-prepared ortho-quinodimethanes. Two different synthetic approaches were designed and followed for the preparation of these adducts. All fullerene derivatives were characterized via 1H- and 13C-NMR, matrix-assisted laser desorption-ionization mass spectrometry, as well as, by FT-IR and UV-Vis spectroscopies and cyclic voltammetry. All adducts exert very high solubility in common organic solvents like chloroform, tetrahydrofuran, and toluene.

A New Family of Fullerene Derivatives Bearing Long Alkyl and Triethyleneglycol Moieties

The research project was supported by the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the "1st Call for H.F.R.I. Research Projects to support Faculty Members & Researchers and the procurement of high-cost research equipment grant" (Project Number: 16.Acronym: SUSTAIN). We thank Professor Thomas Mavromoustakos for his advice and support concerning the calculation of the relaxation delay times for the NMR analysis related to the kinetic isotope effect measurements. We also acknowledge the contribution of COST Action CA15106 (C-H Activation in Organic Synthesis.CHAOS). We also thank the Spanish Ministerio de Ciencia e Innovacion (PID2019-110008GB-I00) and IZO-SGI SGIker of UPV/EHU for financial and human support. The Special Account for Research Grants of the National and Kapodistrian University of Athens is also gratefully acknowledged for funding (research program 70/4/17454).

Zinc Iodide Catalyzed Synthesis of Trisubstituted Allenes from Terminal Alkynes and Ketones.

Graphene Nanoribbons: Towards Graphitic Materials with Predefined Dimensions and Electronic Properties

Editorial (Thematic Issue: Recent Developments in Olefin Metathesis)

From the point of view of an organic chemist, the discovery of novel and efficient carbon-carbon bond forming reactions is a continuous scientific quest. Olefin metathesis, a metal-catalyzed reaction, can be considered as one of the most robust tools in this respect. As a result, metathesis has been widely used over various chemistry and materials science fields. The increased popularity of this powerful transformation is mostly due to the development of highly efficient, functional group tolerant, and air- and moisture-stable ruthenium catalysts. However, the complete removal of ruthenium from the reaction products, in order to avoid undesired side-reactions, isomerization, or even the decomposition of products, is very often a highly challenging task. The present article focuses on the most straightforward and efficient methodologies for the removal of ruthenium residues from olefin metathesis post reaction mixtures. These purification protocols can be easily carried out in any common organic synthesis laboratory, needless of specialized reagents and experimental setup.

Georgios C. Vougioukalakis

Papers

A New Family of Fullerene Derivatives Bearing Long Alkyl and Triethyleneglycol Moieties

Zinc Iodide Catalyzed Synthesis of Trisubstituted Allenes from Terminal Alkynes and Ketones.

Graphene Nanoribbons: Towards Graphitic Materials with Predefined Dimensions and Electronic Properties

Editorial (Thematic Issue: Recent Developments in Olefin Metathesis)

Purification of Olefin Metathesis Reaction Products via Straightforward and Low-Cost Protocols