Control of photoisomerization of CC double bond by hydrogen bonding and photoinduced hydrogen atom transfer

2007 ◽  
Vol 20 (11) ◽  
pp. 864-871 ◽  
Author(s):  
Yousuke Azechi ◽  
Keiko Takemura ◽  
Yoshihiro Shinohara ◽  
Yoshinobu Nishimura ◽  
Tatsuo Arai
Keyword(s):  
Hydrogen Bonding ◽  
Double Bond ◽  
Hydrogen Atom ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer

L'isomérisation de radicaux insaturés. II. Les radicaux α-éthallyles et α,γ-diméthallyles formés dans la photolyse de l'hexène-3 et du méthyl-4-pentène-2 à 147,0 et 184,9 nm

1985 ◽  
Vol 63 (4) ◽  
pp. 944-950 ◽  
Author(s):  
Guy J. Collin ◽  
Hélène Deslauriers
Keyword(s):  
Double Bond ◽  
Hydrogen Atom ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer ◽  
Fragmentation Pattern ◽  
Isomerization Process

The photolysis of cis-3-hexene and 4-methyl-cis-2-pentene has been studied at 147.0 and 184.9 nm. The fragmentation pattern of the photoexcited molecule is normal: it requires, mainly, the split of a C—C bond located in the β position relative to the double bond [Formula: see text]. Some α(C—C), β(C—H), and α(C—H) primary splits complete this mechanism. The formation of α-ethallyl and α,γ-dimethallyl radicals is important in 3-hexene and 4-methyl-2-pentene, respectively. An isomerization process, involving these two radicals, is necessary to explain the formation of part of the 1,3-pentadiene in the 3-hexene system and of all the 1,3-butadiene in the 4-methyl-2-pentene system. This process involves a 1,4-hydrogen atom transfer.

scholarly journals Visible light-mediated difluoroalkylation of electron-deficient alkenes

2018 ◽  
Vol 14 ◽  
pp. 1637-1641 ◽  
Author(s):  
Vyacheslav I Supranovich ◽  
Vitalij V Levin ◽  
Marina I Struchkova ◽  
Jinbo Hu ◽  
Alexander D Dilman
Keyword(s):  
Double Bond ◽  
Hydrogen Atom ◽  
Visible Light ◽  
Blue Light ◽  
Radical Addition ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer ◽  
Sodium Cyanoborohydride

A method for the reductive difluoroalkylation of electron-deficient alkenes using 1,1-difluorinated iodides mediated by irradiation with blue light is described. The reaction involves radical addition of 1,1-difluorinated radicals at the double bond followed by hydrogen atom transfer from sodium cyanoborohydride.

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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