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.

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

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>

Catalytic Synthesis of Cyclic Guanidines via Hydrogen Atom Transfer and Radical-Polar Crossover

2020 ◽  
Author(s):  
Shunya Ohuchi ◽  
Hiroki Koyama ◽  
Hiroki Shigehisa
Keyword(s):  
Hydrogen Atom ◽  
Functional Group ◽  
Hydrogen Atom Transfer ◽  
Catalytic Synthesis ◽  
Membered Ring ◽  
Biologically Active ◽  
Atom Transfer ◽  
Powerful Method ◽  
Protective Groups ◽  
The Common

A catalytic synthesis of cyclic guanidines, which are found in many biologically active compounds and natu-ral products, was developed, wherein transition-metal hydrogen atom transfer and radical-polar crossover were employed. This mild and functional-group tolerant process enabled the cyclization of alkenyl guanidines bearing common protective groups, such as Cbz and Boc. This powerful method not only provided the common 5- and 6-membered rings but also an unusual 7-membered ring. The derivatization of the products afforded various heterocycles. We also investigated the se-lective cyclization of mono-protected or hetero-protected (TFA and Boc) alkenyl guanidines and their further derivatiza-tions.

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.

Sign in / Sign up

Export Citation Format

Share Document