ChemInform Abstract: Isoselectivity Correlation for the Stereoselectivity of the Hydrogen Atom Transfer to Cyclic Alkyl Radicals.

ChemInform ◽  
2010 ◽  
Vol 22 (29) ◽  
pp. no-no
Author(s):  
B. GIESE ◽  
H. FARSHCHI ◽  
J. HARTMANNS ◽  
J. O. METZGER
Keyword(s):  
Hydrogen Atom ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer ◽  
Alkyl Radicals

scholarly journals Titanium and Cobalt Bimetallic Radical Redox Relay for the Isomerization of N-Bz Aziridines to Allylic Amides

Synthesis ◽  
2021 ◽  
Author(s):  
Song Lin ◽  
Devin P. Wood ◽  
Weiyang Guan
Keyword(s):  
Hydrogen Atom ◽  
Hydrogen Atom Transfer ◽  
Alternative Strategy ◽  
Atom Transfer ◽  
Allylic Amination ◽  
Alkyl Radicals ◽  
Mild Conditions

AbstractHerein a bimetallic radical redox-relay strategy is employed to generate alkyl radicals under mild conditions with titanium(III) catalysis and terminated via hydrogen atom transfer with cobalt(II) catalysis to enact base-free isomerizations of N-Bz aziridines to N-Bz allylic amides. This reaction provides an alternative strategy for the synthesis of allylic amides from alkenes via a three-step sequence to accomplish a formal transpositional allylic amination.

Iminyl radicals in gas-phase synthesis. II. Formation of a-branched nitriles from cycloalkanone azines

1976 ◽  
Vol 29 (10) ◽  
pp. 2289 ◽  
Author(s):  
WD Crow ◽  
AN Khan
Keyword(s):  
Hydrogen Atom ◽  
Gas Phase ◽  
Hydrogen Atom Transfer ◽  
Ring Cleavage ◽  
Atom Transfer ◽  
Phase Synthesis ◽  
Alkyl Radicals ◽  
Gas Phase Synthesis ◽  
Internal Hydrogen

Gas-phase pyrolysis of cyclopentanone and cyclohexanone azines results in the formation of iminyl radicals. These undergo ring cleavage to the ω-cyanoalkyl radicals, which stabilize, by internal hydrogen-atom transfer, to the corresponding α-cyanoalkyl radicals. Fragmentation of the latter yields acrylonitrile and alkyl radicals, which can recombine with the α-cyanoalkyl radicals to form α-alkylated nitriles. The mechanisms involved are discussed with reference to isotopic labellingstudies.

Reactions of alkoxy radicals. IV. Intramolecular hydrogen-atom transfer in the presence of cupric ion: A novel directive effect

1964 ◽  
Vol 17 (12) ◽  
pp. 1342 ◽  
Author(s):  
B Acott ◽  
ALJ Beckwith
Keyword(s):  
Hydrogen Atom ◽  
Metal Ion ◽  
Hydrogen Atom Transfer ◽  
Ferrous Ion ◽  
Atom Transfer ◽  
Unsaturated Alcohol ◽  
Alkoxy Radicals ◽  
Alkyl Radicals ◽  
Cupric Ion ◽  
Intramolecular Hydrogen

2-Methyl-2-hexyloxy radical (V), generated by ferrous-ion reduction of 2-methyl-2-hexyl hydroperoxide, undergoes intramolecular hydrogen-atom transfer to the extent of 44%, yielding 2-hydroxy-2-methyl-5-hexyl radical (XIII). Oxidation of the latter with cupric ion in acetic acid affords a mixture of 2-methyl-4-hexen-2-ol (XXI) and 2-methyl-5-hexen-2-ol (XX). Similar results were obtained using radicals derived from 2,5-dimethyl-2-hexyl hydroperoxide and 2-methyl-2-heptyl hydroperoxide. In each case the preponderant formation of the unsaturated alcohol having an olefinic link in the δ-position with respect to the hydroxy group demonstrates the operation of a novel directive effect, for which a possible mechanism is discussed. Some other examples of metal-ion oxidation of alkyl radicals are described. No product arising from intramolecular hydrogen-atom transfer was isolated from ferrous-ion reduction of 2,4,4-trimethyl-2-pentyl hydroperoxide.

Direct Cyclization of Alkenyl Thioester via Transition Metal‐hydrogen Atom Transfer/radical‐polar Crossover Mechanism

2019 ◽  
Author(s):  
Shiori Date ◽  
Kensei Hamasaki ◽  
Karen Sunagawa ◽  
Hiroki Koyama ◽  
Chikayoshi Sebe ◽  
...  
Keyword(s):  
Natural Products ◽  
Hydrogen Atom ◽  
Transition Metal ◽  
Hydrogen Atom Transfer ◽  
Synthetic Method ◽  
Atom Transfer ◽  
Reaction Conditions ◽  
Hydride Hydrogen ◽  
Sulfur Heterocycles ◽  
One Step

<div>We report here a catalytic, Markovnikov selective, and scalable synthetic method for the synthesis of saturated sulfur heterocycles, which are found in the structures of pharmaceuticals and natural products, in one step from an alkenyl thioester. Unlike a potentially labile alkenyl thiol, an alkenyl thioester is stable and easy to prepare. The powerful Co catalysis via a cobalt hydride hydrogen atom transfer and radical-polar crossover mechanism enabled simultaneous cyclization and deprotection. The substrate scope was expanded by the extensive optimization of the reaction conditions and tuning of the thioester unit.</div>

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