scholarly journals Recent Advances in Enantioselective Photochemical Reactions of Stabilized Diazo Compounds

Molecules ◽  
2019 ◽  
Vol 24 (17) ◽  
pp. 3191 ◽  
Author(s):  
Ting-Bi Hua ◽  
Qing-Qing Yang ◽  
You-Quan Zou
Keyword(s):  
Photochemical Reactions ◽  
Diazo Compounds ◽  
Reaction Type ◽  
The Past ◽  
Recent Advances ◽  
Wide Range ◽  
Metal Carbenoids ◽  
Metal Catalyzed ◽  
Made In

Diazo compounds have proven to be a useful class of carbenes or metal carbenoids sources under thermal, photochemical, or metal-catalyzed conditions, which can subsequently undergo a wide range of synthetically important transformations. Recently, asymmetric photocatalysis has provoked increasing research interests, and great advances have been made in this discipline towards the synthesis of optically enriched compounds. In this context, the past two decades have been the most productive period in the developments of enantioselective photochemical reactions of diazo compounds due to a better understanding of the reactivities of diazo compounds and the emergence of new catalytic modes, as well as easier access to and treatment of stabilized diazo compounds. This review highlights these impressive achievements according to the reaction type, and the general mechanisms and stereochemical inductions are briefly discussed as well.

Recent Advances in Denitrogenative Reactions of Pyridotriazoles

Synthesis ◽  
2020 ◽  
Vol 52 (23) ◽  
pp. 3564-3576 ◽  
Author(s):  
Ilya P. Filippov ◽  
Gleb D. Titov ◽  
Nikolai V. Rostovskii
Keyword(s):  
Lewis Acids ◽  
Heterocyclic Compounds ◽  
Short Review ◽  
Diazo Compounds ◽  
Metal Compounds ◽  
The Past ◽  
Recent Advances ◽  
Catalyzed Reactions ◽  
Metal Catalyzed ◽  
Chain Isomerization

AbstractDiazo compounds display versatile reactivity and therefore are widely used in organic synthesis. Diazo compounds bearing a 2-pyridyl or a related azine moiety on the diazo carbon exist in the form of fused 1,2,3-triazoles. In this short review, we summarize the recent advances in denitrogenative reactions of [1,2,3]triazolo[1,5-a]pyridines (‘pyridotriazoles’) and related fused 1,2,3-triazoles. Over the past decade, there has been a surge of activity in this field, with novel denitrogenative reactions of pyridotriazoles induced by metal compounds, light, and Brønsted and Lewis acids having been devised. As a result, heterocyclic compounds and functionalized α-picolines as well as bio­active molecules have been synthesized. In the review, emphasis is also placed on the mechanisms of the new reactions.1 Introduction2 Ring-Chain Isomerization of Pyridotriazoles3 Metal-Catalyzed Reactions3.1 Rh(II) Catalysis3.2 Rh(III) Catalysis3.3 Cu Catalysis3.4 Pd Catalysis3.5 Catalysis by Other Metals4 Metal-Free Reactions5 Conclusion

Recent advances in B–H functionalization of icosahedral carboranes and boranes by transition metal catalysis

2018 ◽  
Vol 90 (4) ◽  
pp. 733-744 ◽  
Author(s):  
Simon Duttwyler
Keyword(s):  
Transition Metal ◽  
Direct Conversion ◽  
Significant Progress ◽  
Cage Compounds ◽  
Metal Catalysis ◽  
Boron Clusters ◽  
The Past ◽  
Recent Advances ◽  
Metal Catalyzed ◽  
Made In

AbstractSignificant progress in the functionalization of icosahedral boron clusters has been made in the past years, leading to an increasing number of applications in various fields of research. The direct conversion of B–H bonds to substituted vertices constitutes an attractive strategy to synthesize cage compounds with desired properties. In this report, recent advances in the transition metal-catalyzed B–H activation of neutral and anionic boron clusters are presented.

scholarly journals Recent Advances in Palladium-Catalyzed Isocyanide Insertions

Molecules ◽  
2020 ◽  
Vol 25 (21) ◽  
pp. 4906
Author(s):  
Jurriën W. Collet ◽  
Thomas R. Roose ◽  
Bram Weijers ◽  
Bert U. W. Maes ◽  
Eelco Ruijter ◽  
...  
Keyword(s):  
Organic Synthesis ◽  
Building Blocks ◽  
Insertion Reactions ◽  
Chemical Reagents ◽  
The Past ◽  
Recent Advances ◽  
Recent Developments ◽  
Palladium Catalyzed ◽  
Made In ◽  
Rapid Incorporation

Isocyanides have long been known as versatile chemical reagents in organic synthesis. Their ambivalent nature also allows them to function as a CO-substitute in palladium-catalyzed cross couplings. Over the past decades, isocyanides have emerged as practical and versatile C1 building blocks, whose inherent N-substitution allows for the rapid incorporation of nitrogeneous fragments in a wide variety of products. Recent developments in palladium catalyzed isocyanide insertion reactions have significantly expanded the scope and applicability of these imidoylative cross-couplings. This review highlights the advances made in this field over the past eight years.

The UK Government’s Global Partnership Programme: Its Achievements Over the Past Five Years and Challenges Ahead

2007 ◽  
Author(s):  
Alan Heyes
Keyword(s):  
Significant Contribution ◽  
Weapons Of Mass Destruction ◽  
Chemical Weapons ◽  
The European Union ◽  
The Past ◽  
Global Partnership ◽  
Wide Range ◽  
Nuclear Security ◽  
The Uk ◽  
Made In

Through the Global Partnership the UK continues to make a significant contribution to improve national and global security. Over the past year the UK has continued to implement a wide range of projects across the breadth of its Global Partnership Programme. As well as ensuring the Programme is robust and capable of dealing with new challenges, the UK has cooperated with other donor countries to help them progress projects associated with submarine dismantling, scientist redirection, enhancing nuclear security and Chemical Weapons Destruction. The Global Partnership, although only five years old, has already achieved a great deal. Some 23 states, plus the European Union, are now working closer together under the Global Partnership, and collectively have enhanced global regional and national security by reducing the availability of Weapons of Mass Destruction (WMD) materials and expertise to both states of concern and terrorists. Considerable progress has already been made in, for example: • Improving the security of fissile materials, dangerous biological agents and chemical weapons stocks; • Reducing the number of sites containing radioactive materials; • Working towards closure of reactors still producing weapon-grade plutonium; • Improving nuclear safety to reduce the risks of further, Chernobyl style accidents; • Constructing facilities for destroying Chemical Weapons stocks, and starting actual destruction; • Providing sustainable employment for former WMD scientists to reduce the risk that their expertise will be misused by states or terrorists. By contributing to many of these activities, the UK has helped to make the world safer. This paper reports on the UK’s practical and sustainable contribution to the Global Partnership and identifies a number of challenges that remain if it is to have a wider impact on reducing the threats from WMD material.

Recent Advances in Glass Transitions in Polymers

1970 ◽  
Vol 43 (1) ◽  
pp. 156-170 ◽  
Author(s):  
A. Eisenberg ◽  
M. Shen
Keyword(s):  
Glass Transition ◽  
Present Article ◽  
Progress Report ◽  
Previous Article ◽  
Glass Transitions ◽  
The Past ◽  
Recent Advances ◽  
Made In

Abstract Since the publication of our review “Glass Transition in Polymers” in 1966, a number of interesting advances have been made in this field. The present article is intended to be an addendum to this review, reporting the progress that has been made by various workers during the past three years. In addition, a number of topics were not covered in the previous article due to the relatively incomplete understanding at that time. These will now be discussed. This is not because these topics are at present fully understood. Rather, we hope it will serve as a progress report to stimulate further interest in areas where further work is needed. The numbering systems and notations in this paper will follow those in the previous article for the sake of continuity.

scholarly journals Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

2021 ◽  
Vol 17 ◽  
pp. 2462-2476
Author(s):  
Yi Liu ◽  
Puying Luo ◽  
Yang Fu ◽  
Tianxin Hao ◽  
Xuan Liu ◽  
...  
Keyword(s):  
Reaction Mechanisms ◽  
Structural Motifs ◽  
Pyrrole Derivatives ◽  
The Past ◽  
Recent Advances ◽  
Functionalized Pyridine ◽  
Great Progress ◽  
Made In

Great progress has been made in the tandem annulation of enynes in the past few years. This review only presents the corresponding reactions of 1,3-enyne structural motifs to provide the functionalized pyridine and pyrrole derivatives. The functionalization reactions cover iodination, bromination, trifluoromethylation, azidation, carbonylation, arylation, alkylation, selenylation, sulfenylation, amidation, esterification, and hydroxylation. We also briefly introduce the applications of the products and the reaction mechanisms for the synthesis of corresponding N-heterocycles.

Toward a Medical Understanding of Marihuana

1969 ◽  
Vol 14 (6) ◽  
pp. 591-600 ◽  
Author(s):  
Conrad J. Schwarz
Keyword(s):  
English Language ◽  
Medical Literature ◽  
Experimental Studies ◽  
Personal Characteristics ◽  
Short Term ◽  
The Past ◽  
Wide Range ◽  
Indian Hemp ◽  
Made In

This paper is based on a review of the English language medical literature over the past 35 years on Indian Hemp, with direct reference being made to the more significant articles published during that time. The paucity of direct experimental observation is noted and the difficulties in experimental studies are highlighted by descriptions of the wide variations in the potency of Indian Hemp derivatives. Specific references are provided for the wide range of observations made in relation to acute and chronic physical and psychological effects, personal characteristics of the users and possible factors in causation. It is concluded that marihuana is a poorly defined intoxicant which varies in potency, deteriorates with time and whose chemical composition is largely unknown at present. There are wide variations in human response and the state of intoxication itself carries with it varying degrees of unpleasant physical and psychological experiences. The association between hashish and, to a lesser extent, marihuana and short-term and long-term complications is discussed in relation to complex variables, of which the drug is but one factor.

Endogenous evoked potentials assessment in depression: a review

1996 ◽  
Vol 11 (7) ◽  
pp. 357-368 ◽  
Author(s):  
JL Nandrino ◽  
F El Massioui ◽  
J Everett
Keyword(s):  
Evoked Potentials ◽  
Cognitive Functions ◽  
Event Related Potentials ◽  
The Past ◽  
Recent Advances ◽  
Cognitive Operations ◽  
Wide Range ◽  
Related Potentials ◽  
Methodological Problems ◽  
Specific Disorders

SummaryOver the past 15 years, researchers have shown an increasing interest in using event-related potentials (ERPs) to study depression. These studies generally fall into four classes: 1), ERPs as a means of detecting depression; 2), ERPs as a tool for distinguishing subtypes of depression; 3), ERPs as a measure of pharmacological effectiveness; 4), ERPs as indicators of defective cognitive operations in depressed subjects. Results from these heterogeneous approaches are often inconsistent and disappointing. Although some ERP components often show increased latencies and diminished amplitudes, these changes seem to reflect principally a variety of non-specific disorders affecting a wide range of cognitive functions rather than a precise and consistent deficit of a particular function. These disappointing results seem to be attributable to methodological problems (heterogeneous patient populations, disproportionate use of the odd-ball paradigm), and do not necessarily call into question the value of studying the ERPs. Furthermore, recent advances in ERP methodology have opened up new perspectives for ERP use in psychopathology.

scholarly journals Recent advances in the synthesis of α-amino ketones

2021 ◽  
Author(s):  
Lewis A. T. Allen ◽  
Robert-Cristian Raclea ◽  
Philipp Natho ◽  
Philip J. Parsons
Keyword(s):  
Functional Group ◽  
Amino Ketone ◽  
Product Substitution ◽  
The Past ◽  
Recent Advances ◽  
Extended Discussion ◽  
Made In

This review on α-amino ketone synthesis collates and evaluates developments made in this area over the past decade, with an extended discussion on functional group compatibility, resultant product substitution patterns, and medicinal applications.

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