ChemInform Abstract: RELATIVE REACTIVITIES OF HETARYL RADICALS IN HYDROGEN ATOM ABSTRACTION AND NUCLEOPHILIC ADDITION REACTIONS

1984 ◽  
Vol 15 (18) ◽  
Author(s):  
J. A. ZOLTEWICZ ◽  
G. A. LOCKO
Keyword(s):  
Hydrogen Atom ◽  
Nucleophilic Addition ◽  
Hydrogen Atom Abstraction ◽  
Addition Reactions

7 Electrochemically Generated Nitrogen-Centered Radicals

2022 ◽  
Author(s):  
Z.-W. Hou ◽  
H.-C. Xu
Keyword(s):  
Hydrogen Atom ◽  
Organic Synthesis ◽  
Recent Progress ◽  
Reactive Intermediates ◽  
Hydrogen Atom Abstraction ◽  
Addition Reactions ◽  
Electrochemical Generation ◽  
Nitrogen Containing Compounds

Nitrogen-centered radicals are versatile reactive intermediates for organic synthesis. This chapter describes recent progress in the electrochemical generation and reactions of nitrogen-centered radicals. Under electrochemical conditions, various nitrogen-centered radicals are generated through electrolysis of readily available precursors such as N—H bonds or azides. These reactive intermediates undergo addition reactions to π-systems or hydrogen-atom abstraction to generate various nitrogen-containing compounds.

Hydrogen atom abstraction and addition reactions of charged phenyl radicals with aromatic substrates in the gas phase

2001 ◽  
Vol 210-211 ◽  
pp. 511-520 ◽  
Author(s):  
Luis E. Ramı́rez-Arizmendi ◽  
Leo Guler ◽  
Joseph J. Ferra ◽  
Kami K. Thoen ◽  
Hilkka I. Kenttämaa
Keyword(s):  
Hydrogen Atom ◽  
Gas Phase ◽  
Hydrogen Atom Abstraction ◽  
Addition Reactions ◽  
Phenyl Radicals ◽  
Aromatic Substrates

2-Deoxyribose Radicals in the Gas Phase and Aqueous Solution. Transient Intermediates of Hydrogen Atom Abstraction from 2-Deoxyribofuranose

2005 ◽  
Vol 70 (11) ◽  
pp. 1769-1786 ◽  
Author(s):  
Luc A. Vannier ◽  
Chunxiang Yao ◽  
František Tureček
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Atom ◽  
Gas Phase ◽  
Computational Study ◽  
Hydrogen Atom Abstraction ◽  
Oh Radical ◽  
Free Energies ◽  
Intramolecular Hydrogen ◽  
Solvation Free Energies ◽  
Transient Intermediates

A computational study at correlated levels of theory is reported to address the structures and energetics of transient radicals produced by hydrogen atom abstraction from C-1, C-2, C-3, C-4, C-5, O-1, O-3, and O-5 positions in 2-deoxyribofuranose in the gas phase and in aqueous solution. In general, the carbon-centered radicals are found to be thermodynamically and kinetically more stable than the oxygen-centered ones. The most stable gas-phase radical, 2-deoxyribofuranos-5-yl (5), is produced by H-atom abstraction from C-5 and stabilized by an intramolecular hydrogen bond between the O-5 hydroxy group and O-1. The order of radical stabilities is altered in aqueous solution due to different solvation free energies. These prefer conformers that lack intramolecular hydrogen bonds and expose O-H bonds to the solvent. Carbon-centered deoxyribose radicals can undergo competitive dissociations by loss of H atoms, OH radical, or by ring cleavages that all require threshold dissociation or transition state energies >100 kJ mol-1. This points to largely non-specific dissociations of 2-deoxyribose radicals when produced by exothermic hydrogen atom abstraction from the saccharide molecule. Oxygen-centered 2-deoxyribose radicals show only marginal thermodynamic and kinetic stability and are expected to readily fragment upon formation.

scholarly journals A cross-dehydrogenative C(sp3)−H heteroarylation via photo-induced catalytic chlorine radical generation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Chia-Yu Huang ◽  
Jianbin Li ◽  
Chao-Jun Li
Keyword(s):  
Hydrogen Atom ◽  
Hydrogen Evolution ◽  
Alkyl Radical ◽  
Cobalt Catalyst ◽  
Alkylation Reaction ◽  
Hydrogen Atom Abstraction ◽  
Dehydrogenative Coupling ◽  
Radical Generation ◽  
Limited Scope

AbstractHydrogen atom abstraction (HAT) from C(sp3)–H bonds of naturally abundant alkanes for alkyl radical generation represents a promising yet underexplored strategy in the alkylation reaction designs since involving stoichiometric oxidants, excessive alkane loading, and limited scope are common drawbacks. Here we report a photo-induced and chemical oxidant-free cross-dehydrogenative coupling (CDC) between alkanes and heteroarenes using catalytic chloride and cobalt catalyst. Couplings of strong C(sp3)–H bond-containing substrates and complex heteroarenes, have been achieved with satisfactory yields. This dual catalytic platform features the in situ engendered chlorine radical for alkyl radical generation and exploits the cobaloxime catalyst to enable the hydrogen evolution for catalytic turnover. The practical value of this protocol was demonstrated by the gram-scale synthesis of alkylated heteroarene with merely 3 equiv. alkane loading.

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