Free-radical reduction reactions of chiral dihydronicotinamides. Enantioselective hydrogen atom transfer and electron-transfer processes during the reduction of ketones

1988 ◽  
Vol 110 (9) ◽  
pp. 2968-2970 ◽  
Author(s):  
Dennis D. Tanner ◽  
Abdelmajid. Kharrat
Keyword(s):  
Electron Transfer ◽  
Free Radical ◽  
Hydrogen Atom ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer ◽  
Reduction Reactions ◽  
Transfer Processes ◽  
Radical Reduction ◽  
Electron Transfer Processes ◽  
Reduction Of Ketones

On the electron transfer and hydrogen atom abstraction mechanism for 1-benzyl-1,4-dihydronicotinamide reduction of benzoquinones

1990 ◽  
Vol 68 (10) ◽  
pp. 1662-1667 ◽  
Author(s):  
Dennis D. Tanner ◽  
Abdelmajid Kharrat ◽  
H. Oumar-Mahamat
Keyword(s):  
Electron Transfer ◽  
Free Radical ◽  
Hydrogen Atom ◽  
Hydrogen Atom Transfer ◽  
Chain Process ◽  
Single Electron Transfer ◽  
Second Order Reaction ◽  
Radical Chain ◽  
Radical Reduction ◽  
Radical Chain Process

The reduction of p-benzoquinone (BQ) by 1-benzyl-1,4-dihydronicotinamide (BNAH) proceeds by a free-radical chain mechanism initiated by single electron transfer (SET). In dry deoxygenated acetonitrile, the chain, whose propagation steps contain a SET–hydrogen atom transfer sequence, could be inhibited by dinitrobenzene and initiated by di-tert-butylperoxyoxalate. The reduction does not follow second-order reaction kinetics. The fractional order of each reactant was found to be 0.80 and 1.36 for BNAH and BQ, respectively. The AG0 values for both the initiation and the propagation steps were evaluated electro-chemically (CV) and were found to be of a reasonable magnitude to sustain a free-radical chain process. Keywords: 1-benzyl-1,4-dihydronicotinamide, p-benzoquinone, free radical, reduction.

Sulfamides Direct Radical-Mediated Chlorination of Aliphatic C–H Bonds

2019 ◽  
Author(s):  
Melanie Short ◽  
Mina Shehata ◽  
Matthew Sanders ◽  
Jennifer Roizen
Keyword(s):  
Hydrogen Atom ◽  
Transfer Reaction ◽  
Hydrogen Atom Transfer ◽  
Chain Propagation ◽  
Propagation Mechanism ◽  
Atom Transfer ◽  
Radical Chain ◽  
Radical Intermediates ◽  
Transfer Processes ◽  
Unusual Position

Sulfamides guide intermolecular chlorine transfer to gamma-C(sp<sup>3</sup>) centers. This unusual position-selectivity arises because accessed sulfamidyl radical intermediates engage in otherwise rare 1,6-hydrogen-atom transfer processes. The disclosed chlorine-transfer reaction relies on a light-initiated radical chain-propagation mechanism to oxidize C(sp<sup>3</sup>)-H bonds.

Sulfamides Direct Radical-Mediated Chlorination of Aliphatic C–H Bonds

2019 ◽  
Author(s):  
Melanie Short ◽  
Mina Shehata ◽  
Matthew Sanders ◽  
Jennifer Roizen
Keyword(s):  
Hydrogen Atom ◽  
Transfer Reaction ◽  
Hydrogen Atom Transfer ◽  
Chain Propagation ◽  
Propagation Mechanism ◽  
Atom Transfer ◽  
Radical Chain ◽  
Radical Intermediates ◽  
Transfer Processes ◽  
Unusual Position

Sulfamides guide intermolecular chlorine transfer to gamma-C(sp<sup>3</sup>) centers. This unusual position-selectivity arises because accessed sulfamidyl radical intermediates engage in otherwise rare 1,6-hydrogen-atom transfer processes. The disclosed chlorine-transfer reaction relies on a light-initiated radical chain-propagation mechanism to oxidize C(sp<sup>3</sup>)-H bonds.

scholarly journals Thiyl and phenoxyl free radicals and NADH Direct observation of one-electron oxidation

1986 ◽  
Vol 240 (3) ◽  
pp. 897-903 ◽  
Author(s):  
L G Forni ◽  
R L Willson
Keyword(s):  
Electron Transfer ◽  
Free Radicals ◽  
Hydrogen Atom ◽  
Pulse Radiolysis ◽  
Biological Significance ◽  
Transfer Reactions ◽  
Absolute Rate ◽  
Transfer Processes ◽  
Biochemical Systems ◽  
Electron Transfer Processes

Absolute rate constants for the reaction of NADH with thiyl free radicals derived from various sulphur-containing compounds of biological significance were measured by using the technique of pulse radiolysis. These and related reactions with phenoxyl free radicals are believed to occur through one-electron-transfer processes. Further evidence comes from studies with deuterated NADH. The results support the possibility that, in biochemical systems, thiols may act as catalysts linking hydrogen-atom and electron-transfer reactions.

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