The mechanism of alkyl radical loss from ionised pentenyl methyl and hexenyl methyl ethers: the importance of a 1,2-hydrogen shift to the radical site of a distonic ion

1992 ◽  
pp. 96 ◽  
Author(s):  
Richard D. Bowen ◽  
Andrew D. Wright
Keyword(s):  
Alkyl Radical ◽  
Radical Site ◽  
Hydrogen Shift ◽  
Distonic Ion

Bimolecular reactions involving the radical site of the distonic ion ·CH2CH2CH2CO+

1993 ◽  
Vol 7 (5) ◽  
pp. 392-399 ◽  
Author(s):  
Krista M. Stirk ◽  
Rebecca L. Smith ◽  
Joe C. Orlowski ◽  
Hilkka I. Kenttämaa
Keyword(s):  
Bimolecular Reactions ◽  
Radical Site ◽  
Distonic Ion

Regiospecific addition of CH2O at the radical site of the˙CH2CH2OHCH3+ distonic ion

1995 ◽  
Vol 30 (12) ◽  
pp. 1747-1751 ◽  
Author(s):  
V. Troude ◽  
D. Leblanc ◽  
P. Mourgues ◽  
H. E. Audier
Keyword(s):  
Radical Site ◽  
Distonic Ion

Investigation of the mechanism of alkyl radical elimination from ionised pentenyl methyl and hexenyl methyl ethers by analysis of the collision-induced dissociation mass spectra of C4H7O+ and C5H9O+ ions

1993 ◽  
Vol 71 (7) ◽  
pp. 1073-1085 ◽  
Author(s):  
Andrew D. Wright ◽  
Richard D. Bowen
Keyword(s):  
Alkyl Radical ◽  
Mass Spectra ◽  
General Structure ◽  
Alkyl Substituent ◽  
Frontier Molecular Orbital ◽  
Collision Induced Dissociation ◽  
Methyl Radical ◽  
Distonic Ions ◽  
Product Ions ◽  
Distonic Ion

Collision-induced dissociation (CID) mass spectra are reported for C4H7O+ and C5H9O+ ions generated by loss of an alkyl radical from 11 isomers of C5H9OCH3+• and 8 isomers of C6H11OCH3+• produced by ionisation of alkenyl methyl ethers derived from stable alkenols. The oxonium product ions have acyclic structures (CH=CHCH=O+CH3 for C4H7O+; CH2=CH(CH3)C=O+CH3, CH3CH=CHCH=O+CH3, or CH2=(CH3)CCH=O+CH3 in the case of C5H9O+). Elimination of a methyl radical does not always occur by simple α-cleavage. Expulsion of an alkyl substituent attached to a carbon atom at either end of the C=C double bond also takes place readily; this process sometimes competes with or pre-empts α-cleavage, as is shown by 2H-labelling experiments. Plausible mechanisms for this σ′-cleavage are considered. A route involving a 1,2-H shift to the radical centre of a distonic ion, followed by γ-cleavage of the resultant ionised enol ether, is shown to provide the most accurate unifying description of this unusual fragmentation. The mechanistic significance of this interpretation of the σ′-cleavage is discussed by analysing the reverse reaction (addition of an alkyl radical to a methyl cationated enal) in frontier molecular orbital terms. A comparison is made between the mechanisms by which an alkyl radical is lost from ionised alkenyl methyl ethers by σ′-cleavage and the parallel process starting from ionised carboxylic acids or isomeric distonic ions derived from these CnH2n+1CO2H+• species. Both classes of fragmentation are best understood to occur via γ-cleavage of a distonic ion of general structure R1CH2CH•C+(X)OR2 (R1 = alkyl; X = OH, R2 = H; or X = H, R2 = CH3), thus yielding (R′)• and CH2 = CHC+(X)OR2.

Visible-Light Photosensitized Aryl and Alkyl Decarboxylative Carbon-Heteroatom and Carbon-Carbon Bond Formations

2019 ◽  
Author(s):  
Tuhin Patra ◽  
Satobhisha Mukherjee ◽  
Jiajia Ma ◽  
Felix Strieth-Kalthoff ◽  
Frank Glorius
Keyword(s):  
Energy Transfer ◽  
Visible Light ◽  
Alkyl Radical ◽  
General Strategy ◽  
Alkyl Radicals ◽  
Bond Forming ◽  
Radical Trapping ◽  
Carbon Carbon Bond ◽  
Radical Generation ◽  
Trapping Agent

<sub>A general strategy to access both aryl and alkyl radicals by photosensitized decarboxylation of the corresponding carboxylic acids esters has been developed. An energy transfer mediated homolysis of unsymmetrical sigma-bonds for a concerted fragmentation/decarboxylation process is involved. As a result, an independent aryl/alkyl radical generation step enables a series of key C-X and C-C bond forming reactions by simply changing the radical trapping agent.</sub>

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.

scholarly journals Iron‐Catalyzed Tertiary Alkylation of Terminal Alkynes with 1,3‐Diesters via a Functionalized Alkyl Radical

2021 ◽  
Vol 133 (17) ◽  
pp. 9792-9797
Author(s):  
Ming‐Qing Tian ◽  
Zhen‐Yao Shen ◽  
Xuefei Zhao ◽  
Patrick J. Walsh ◽  
Xu‐Hong Hu
Keyword(s):  
Alkyl Radical ◽  
Terminal Alkynes

scholarly journals Structure and mechanism of galactose oxidase. The free radical site.

1994 ◽  
Vol 269 (40) ◽  
pp. 25095-25105
Author(s):  
A.J. Baron ◽  
C. Stevens ◽  
C. Wilmot ◽  
K.D. Seneviratne ◽  
V. Blakeley ◽  
...  
Keyword(s):  
Free Radical ◽  
Galactose Oxidase ◽  
Radical Site
Sign in / Sign up

Export Citation Format

Share Document