Unlocking the Accessibility of Alkyl Radicals from Boronic Acids through Hydrogen-bond Assisted Organophotoredox Activation

Despite their prevalence in organic synthesis, the application of boronic acids (BAs) as alkyl radical precursors in visible-light assisted photocatalyzed reactions has been limited by their high oxidation potential. This study demonstrates the remarkable ability of amide solvents viz. DMA (N,N-dimethylacetamide) to participate in hydrogen-bonding interactions with BAs, thus enabling the modulation of their oxidation potential towards the generation of alkyl radicals. The developed protocol is simple, robust and demonstrates broad applicability for alkylation, allylation and elimination reactions in batch and continuous flow. The application towards dehydroalanine allows the synthesis of unnatural amino acids. Furthermore, the chemo-selective generation of radical species from BAs, in the presence of boronic ester-containing molecules, is now feasible, endorsing plausible boron-selective (bio-) orthogonal modifications.

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Visible-Light Photosensitized Aryl and Alkyl Decarboxylative Carbon-Heteroatom and Carbon-Carbon Bond Formations

10.26434/chemrxiv.7995983.v1 ◽

2019 ◽

Author(s):

Tuhin Patra ◽

Satobhisha Mukherjee ◽

Jiajia Ma ◽

Felix Strieth-Kalthoff ◽

Frank Glorius

Keyword(s):

Energy Transfer ◽

Visible Light ◽

Alkyl Radical ◽

General Strategy ◽

Alkyl Radicals ◽

Bond Forming ◽

Radical Trapping ◽

Carbon Carbon Bond ◽

Radical Generation ◽

Trapping Agent

<sub>A general strategy to access both aryl and alkyl radicals by photosensitized decarboxylation of the corresponding carboxylic acids esters has been developed. An energy transfer mediated homolysis of unsymmetrical sigma-bonds for a concerted fragmentation/decarboxylation process is involved. As a result, an independent aryl/alkyl radical generation step enables a series of key C-X and C-C bond forming reactions by simply changing the radical trapping agent.</sub>

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Recent advances in the Silver catalysed synthesis of furan and its applications

Current Catalysis ◽

10.2174/2211544709999201019162020 ◽

2020 ◽

Vol 09 ◽

Author(s):

C M A Afsina ◽

Mohan Neetha ◽

Thaipparambil Aneeja ◽

Gopinathan Anilkumar

Keyword(s):

Organic Synthesis ◽

Oxidation Potential ◽

Silver Complexes ◽

Wide Spread ◽

Silver Catalysts ◽

Recent Advances ◽

High Oxidation ◽

Furan Moiety ◽

Anti Fungal ◽

Fragrance Compounds

: Furan and its derivatives find wide-spread application as pharmaceuticals, pigments, dyes, brighteners, flavour & fragrance compounds and insecticides. They also exhibit anti-hyperglycemic, analgesic, anti-inflammatory, antibacterial, anti-fungal and anti-tumour activities. Silver catalysts are nowadays commonly used in organic synthesis due to the high oxidation potential and versatile nature of silver complexes. In this review, we summarise the recent advances in the synthesis and applications of furan moiety using silver catalysis and covers literature from 2015-2020.

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Unlocking the Accessibility of Alkyl Radicals from Boronic Acids through Solvent-Assisted Organophotoredox Activation

ACS Catalysis ◽

10.1021/acscatal.1c02823 ◽

2021 ◽

Vol 11 (17) ◽

pp. 10862-10870 ◽

Cited By ~ 1

Author(s):

Prabhat Ranjan ◽

Serena Pillitteri ◽

Guglielmo Coppola ◽

Monica Oliva ◽

Erik V. Van der Eycken ◽

...

Keyword(s):

Boronic Acids ◽

Alkyl Radicals

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A New Three-Component Photo-Initiating System for Visible Light Recording of Volume Holograms with Single-Pulsed Laser

Polymers ◽

10.3390/polym13203517 ◽

2021 ◽

Vol 13 (20) ◽

pp. 3517

Author(s):

Horst Berneth ◽

Friedrich Karl Bruder ◽

Thomas Fäcke ◽

Sven Hansen ◽

Koichi Kawamura ◽

...

Keyword(s):

Alkyl Radical ◽

Pulsed Laser ◽

Holographic Recording ◽

Radical Species ◽

Holographic Gratings ◽

Initiation System ◽

Volume Holograms ◽

Recording Material ◽

Safranine O ◽

Dye Molecule

Versatile substituted electron-deficient trichloromethylarenes can easily be synthesized and combined with a Safranine O/triarylalkylborate salt to form a highly efficient three-component photo-initiation system that starts free radical polymerization to finally form holographic gratings with a single-pulsed laser. The mechanism of this photo-initiation most likely relies on an electron transfer from the borate salt into the semi-occupied HOMO of the excited dye molecule Safranine O, which after fragmentation generates an initiating alkyl radical and longer-lived dye radical species. This dye radical is most probably oxidized by the newly introduced trichloromethylarene derivative as an electron acceptor. The two generated radicals from one absorbed photon initiate the photopolymerization and form index gratings in a suitable holographic recording material. This process is purely photonic and does not require further non-photonic post treatments.

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Sewage static system influence on the concentrations of nitrogen compounds in unconfined aquifers

Engenharia Sanitaria e Ambiental ◽

10.1590/s1413-415220190342 ◽

2021 ◽

Author(s):

Filipe da Silva Peixoto ◽

Itabaraci Nazareno Cavalcante

Keyword(s):

Groundwater Quality ◽

Total Dissolved Solids ◽

Oxidation Potential ◽

Nitrogen Compounds ◽

Static System ◽

Nitrogenous Compounds ◽

Septic Tanks ◽

Unconfined Aquifers ◽

High Oxidation ◽

Using Data

ABSTRACT This research aimed to investigate the relation between sanitary situation and groundwater quality, using the concentration of nitrogenous compounds. The aquifer studied is unconfined and situated in the periurban zone of Fortaleza (NE Brazil). Through the Geographic Information System (GIS), a relational database was created using data from the IBGE demographic census (2011), to analyze numbers of households linked to septic tanks or rudimentary cesspit. The groundwater quality was evaluated based on nitrogen compounds (N-NH3 +; NO2 -; N-NO3 -), pH, and total dissolved solids (TDS). The highest concentrations of nitrates are found in areas with a higher density of septic tanks and rudimentary cesspit. Furthermore, nitrate was more present in water table above 6.6 m, mainly in the interfluvial zones, which have a high oxidation potential. The results contribute to the loss of contamination, based on the number of households with septic tanks and rudimentary cesspit, in unconfined aquifers, which were more vulnerable to contamination, mainly in peripheric expansions areas in the cities, where the deficit in sewage services tends to be high.

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ChemInform Abstract: β-(Carbonatoxy)alkyl Radicals: A New Subset of β-(Ester)alkyl Radical Fragmentation During Copper(I)-Mediated Synthesis of 1,1-Dichloro-1-alkenes.

ChemInform ◽

10.1002/chin.201501034 ◽

2015 ◽

Vol 46 (1) ◽

Author(s):

Ram N. Ram ◽

Ram K. Tittal

Keyword(s):

Alkyl Radical ◽

Alkyl Radicals ◽

Radical Fragmentation

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Radiation damage in polyethylene as studied by electron spin resonance

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1961.0113 ◽

1961 ◽

Vol 262 (1309) ◽

pp. 207-218 ◽

Cited By ~ 42

Keyword(s):

Electron Spin Resonance ◽

Electron Spin ◽

Alkyl Radical ◽

Room Temperature ◽

Chemical Properties ◽

Resonance Method ◽

Alkyl Radicals ◽

Spin Resonance ◽

Physical And Chemical ◽

Kinetics Of

The electron spin resonance method was employed to study the nature, concentration and kinetics of the disappearance under varying conditions of radicals produced in polyethylene by fast electron irradiation at 77°K. The predominant radical species at 77°K is the alkyl radical —CH 2 —ĊH—CH 2 —. On being warmed to room temperature it disappears rapidly, revealing a more stable unidentified radical. The kinetics of the decay at room temperature of both radicals was observed. Their stabilities were found to vary in polyethylene samples of differing physical and chemical properties. G values for these radicals are given. Comparison was made with spectra obtained under similar conditions with two pure paraffins and a pure olefin to evaluate the effect of crystallinity branching, molecular weight and unsaturation. In the olefin there is evidence for a build-up of allyl radicals due to the encounter of an alkyl radical with main chain unsaturation. This supports the view that alkyl radicals are mobile, and cross-linking occurs when two such radicals meet.

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