scholarly journals Boron: A key element in radical reactions

2007 ◽  
Vol 79 (2) ◽  
pp. 223-233 ◽  
Author(s):  
Philippe Renaud ◽  
Alice Beauseigneur ◽  
Andrea Brecht-Forster ◽  
Barbara Becattini ◽  
Vincent Darmency ◽  
...  
Keyword(s):  
Chain Transfer ◽  
High Sensitivity ◽  
Conjugate Addition ◽  
Radical Reactions ◽  
Radical Chain ◽  
Alkyl Radicals ◽  
Wide Range ◽  
A Chain ◽  
Very High ◽  
Tertiary Alkyl

Boron derivatives are becoming key reagents in radical chemistry. Here, we describe reactions where an organoboron derivative is used as a radical initiator, a chain-transfer reagent, and a radical precursor. For instance, B-alkylcatecholboranes, easily prepared by hydroboration of alkenes, represent a very efficient source of primary, secondary, and tertiary alkyl radicals. Their very high sensitivity toward oxygen- and heteroatom-centered radicals makes them particularly attractive for the development of radical chain processes such as conjugate addition, allylation, alkenylation, and alkynylation. Boron derivatives have also been used to develop an attractive new procedure for the reduction of radicals with alcohols and water. The selected examples presented here demonstrate that boron-containing reagents can efficiently replace tin derivatives in a wide range of radical reactions.

A General Carbonyl Alkylative Amination Process for Tertiary Amine Synthesis

2019 ◽  
Author(s):  
Roopender Kumar ◽  
Nils Floden ◽  
William G. Whitehurst ◽  
Matthew Gaunt
Keyword(s):  
General Solution ◽  
Visible Light ◽  
Tertiary Amine ◽  
Alkyl Halides ◽  
Secondary Amines ◽  
Chain Process ◽  
Alkyl Radicals ◽  
Wide Range ◽  
Iminium Ions ◽  
A Chain

We report a practical and general solution to this long-standing synthetic challenge can be accomplished by addition of alkyl radicals to all alkyl-iminium ions. The process is mediated by the action of visible light and a simple silane reducing agent, establishing a chain process that permits the combination of an extremely wide range of aldehydes and secondary amines with alkyl halides.

A General Carbonyl Alkylative Amination Process for Tertiary Amine Synthesis

2019 ◽  
Author(s):  
Roopender Kumar ◽  
Nils Floden ◽  
William G. Whitehurst ◽  
Matthew Gaunt
Keyword(s):  
General Solution ◽  
Visible Light ◽  
Tertiary Amine ◽  
Alkyl Halides ◽  
Secondary Amines ◽  
Chain Process ◽  
Alkyl Radicals ◽  
Wide Range ◽  
Iminium Ions ◽  
A Chain

We report a practical and general solution to this long-standing synthetic challenge can be accomplished by addition of alkyl radicals to all alkyl-iminium ions. The process is mediated by the action of visible light and a simple silane reducing agent, establishing a chain process that permits the combination of an extremely wide range of aldehydes and secondary amines with alkyl halides.

Direct C–H Functionalization of Heteroarenes via Redox-Neutral Radical Process: A Facile Route to C–C Bonds Formation

Synthesis ◽  
2017 ◽  
Vol 49 (15) ◽  
pp. 3407-3421 ◽  
Author(s):  
Pin Gao ◽  
Yu-Rui Gu ◽  
Xin-Hua Duan
Keyword(s):  
Functional Group ◽  
Radical Reactions ◽  
Neutral Radical ◽  
Alkyl Radicals ◽  
Aryl Radicals ◽  
Mild Conditions ◽  
Wide Range ◽  
Carbon Radicals ◽  
Facile Route ◽  
Radical Functionalization

Aromatic heterocycles are an important class of compounds found in a wide range of natural products, pharmaceutically active molecules and organic materials. Recently, the direct radical functionalization of heteroaromatic C–H bonds has become an efficient and attractive method to access substituted heteroarenes. Especially, redox-neutral radical reactions have attracted much attention of chemists due to their potential advantages such as mild conditions, free of external oxidants, and good functional group tolerance. So far, a series of redox-neutral radical reactions have been developed. In this review, we mainly focus on the recent advance in direct redox-neutral radical C–H functionalization of heteroarenes. Herein, the direct C–H arylation, C–H alkylation, and C–H fluoroalkylation of heteroarenes are represented respectively, providing practical routes to C–C bond formation.1 Introduction2 C–H Arylation of Heteroarenes with Aryl Radicals3 C–H Alkylation of Heteroarenes with Alkyl Radicals4 C–H Fluoroalkylation of Heteroarenes with Fluorine-Containing Carbon Radicals5 Concluding Remarks

Kinetic rate assay of urinary N-acetyl-beta-D-glucosaminidase with 2-chloro-4-nitrophenyl-N-acetyl-beta-D-glucosaminide as substrate.

1988 ◽  
Vol 34 (10) ◽  
pp. 2140-2143 ◽  
Author(s):  
J Makise ◽  
E Saito ◽  
M Obuchi ◽  
M Kanayama ◽  
K Ichikawa ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
High Precision ◽  
Healthy Subjects ◽  
High Sensitivity ◽  
Reference Interval ◽  
Renal Diseases ◽  
Kinetic Rate ◽  
Synthetic Substrate ◽  
Wide Range ◽  
Very High

Abstract In this new procedure for determining the activity of N-acetyl-beta-D-glucosaminidase (EC 3.2.1.30; NAG) in urine, a new synthetic substrate, 2-chloro-4-nitrophenyl-N-acetyl-beta-D-glucosaminide is used. No sample blank is required because the activity is determined kinetically. Very high precision is possible, with CVs of less than 3.8% both within-run and between-run. Glucose, ascorbic acid, bilirubin, bromosulfonphthalein, and phenosulfonphthalein do not interfere. The reference interval (mean +/- 2 SD) for healthy subjects was 1.9-11.1 U per gram of creatinine. NAG activity can be determined over a wide range (2-500 U/L) with high sensitivity. The method is suitable for use with various automated analyzers, and it should be useful for screening for renal diseases.

scholarly journals General Electrochemical Minisci Alkylation of N-Heteroarenes with Alkyl Halides

2022 ◽  
Author(s):  
Jose Aleman
Keyword(s):  
Natural Products ◽  
Functional Group ◽  
Environmentally Friendly ◽  
Building Blocks ◽  
Alkyl Halides ◽  
Alkyl Radicals ◽  
First Time ◽  
Very High ◽  
Tertiary Alkyl

Abstract Herein, we report, for the first time, a general, facile and environmentally friendly Minisci-type alkylation of N-heteroarenes under simple and straightforward electrochemical conditions using widely available alkyl halides as radical precursors. Primary, secondary and tertiary alkyl radicals have shown to be efficiently generated and coupled with a large variety of N-heteroarenes. The method presents a very high functional group tolerance, including various heterocyclic-based natural products, which highlights the robustness of the methodology. This applicability has been further proved in the synthesis of various interesting biologically valuable building blocks. In addition, we have proposed a mechanism based on different proofs and electrochemical evidences.

Observation of Atom Rows in Thorium Pyromellitate Using a Field Emission STEM

1977 ◽  
Vol 35 ◽  
pp. 80-81
Author(s):  
H. Todokoro ◽  
S. Nomura ◽  
T. Komoda
Keyword(s):  
Field Emission ◽  
Amorphous Carbon ◽  
Carbon Film ◽  
Dark Field Image ◽  
Dark Field ◽  
Amorphous Carbon Film ◽  
Atomic Size ◽  
Wide Range ◽  
A Chain

It is interesting to observe polymers at atomic size resolution. Some works have been reported for thorium pyromellitate by using a STEM (1), or a CTEM (2,3). The results showed that this polymer forms a chain in which thorium atoms are arranged. However, the distance between adjacent thorium atoms varies over a wide range (0.4-1.3nm) according to the different authors.The present authors have also observed thorium pyromellitate specimens by means of a field emission STEM, described in reference 4. The specimen was prepared by placing a drop of thorium pyromellitate in 10-3 CH3OH solution onto an amorphous carbon film about 2nm thick. The dark field image is shown in Fig. 1A. Thorium atoms are clearly observed as regular atom rows having a spacing of 0.85nm. This lattice gradually deteriorated by successive observations. The image changed to granular structures, as shown in Fig. 1B, which was taken after four scanning frames.

TEM study of boron additions to cobalt aluminide

1988 ◽  
Vol 46 ◽  
pp. 546-547
Author(s):  
Gerald B. Feldewerth
Keyword(s):  
High Temperature ◽  
Turbine Engines ◽  
Major Drawback ◽  
University Of Missouri ◽  
Specific Strength ◽  
Aerospace Applications ◽  
Wide Range ◽  
Ordered Alloys ◽  
The University ◽  
Very High

In recent years an increasing emphasis has been placed on the study of high temperature intermetallic compounds for possible aerospace applications. One group of interest is the B2 aiuminides. This group of intermetaliics has a very high melting temperature, good high temperature, and excellent specific strength. These qualities make it a candidate for applications such as turbine engines. The B2 aiuminides exist over a wide range of compositions and also have a large solubility for third element substitutional additions, which may allow alloying additions to overcome their major drawback, their brittle nature.One B2 aluminide currently being studied is cobalt aluminide. Optical microscopy of CoAl alloys produced at the University of Missouri-Rolla showed a dramatic decrease in the grain size which affects the yield strength and flow stress of long range ordered alloys, and a change in the grain shape with the addition of 0.5 % boron.

Features of the Christian values ​​system

2004 ◽  
pp. 21-29
Author(s):  
G.V. Pyrog
Keyword(s):  
Public Opinion ◽  
Religious Beliefs ◽  
Religious Values ◽  
Direct Influence ◽  
Moral Norms ◽  
Value System ◽  
Christian Religion ◽  
Mass Consciousness ◽  
Wide Range ◽  
Very High

In domestic scientific and public opinion, interest in religion as a new worldview paradigm is very high. Today's attention to the Christian religion in our society is connected, in our opinion, with the specificity of its value system, which distinguishes it from other forms of consciousness: the idea of ​​God, the absolute, the eternity of moral norms. That is why its historical forms do not receive accurate characteristics and do not matter in the mass consciousness. Modern religious beliefs do not always arise as a result of the direct influence of church preaching. The emerging religious values ​​are absorbed in a wide range of philosophical, artistic, ethical ideas, acting as a compensation for what is generally defined as spirituality. At the same time, the appeal to Christian values ​​became very popular.

A reflection of the polyethnic phenomenon in the Slovak novel of the 21 st century

2019 ◽  
pp. 462-471
Author(s):  
Lyudmila Shirokova
Keyword(s):  
Interpersonal Relations ◽  
Slovak Republic ◽  
Main Character ◽  
Jewish Family ◽  
Wide Range ◽  
Provincial Society ◽  
A Chain ◽  
Middle Generation ◽  
Artistic Quality

The historical polyethnicity of the Slovak society and the connected problems of the interrelations of cultures, ethics, interpersonal relations, are reflected in the works of modern Slovak prose. They are represented most clearly in the novels of middle generation writers P. Rankov, S. Lavrík, P. Krištúfek. They dwell upon the dramatical events of the 20 th century. They cover wide range problems, from the fruitful coexistence of various ethnic groups and their representatives to national contradictions and racial repressions. The artistic quality of the mentioned works, their composition, the way of narrating, the type of the main character, can be highly evaluated. For example, in a novel by P. Rankov the plot, in spite of its linearity, is a chain of episodes in the span of 30 years from the life of the main characters. It reflects not only their fates, but also the historical and political changes of the world they live in. The main female character of a S. Lavrík ’s novel narrates about everyday life and tragedies in the lives of the dwellers of a Slovak town in the Slovak Republic during the war. P. Krištúfek in his novel focuses on several decades from the life of a Slovak-Jewish family and dwellers of a Slovak provincial society with types and relations specific for this milieu.

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