H2O2-Promoted Alkylation of Quinoxalin-2(1H) ones with Styrenes and Dimethyl sulfoxide

Synlett ◽  
2021 ◽  
Author(s):  
Xiaoyang Zhong ◽  
Hua Yao ◽  
BIngqing Wang ◽  
Yan Zhaohua ◽  
Feng Xiong ◽  
...  
Keyword(s):  
Dimethyl Sulfoxide ◽  
Methyl Radical ◽  
Alkyl Radicals ◽  
Simple Protocol

A H2O2-mediated quinoxaline-2(1H)-ones hydrocarbylation reaction has been reported. The reaction is achieved through the difunctionalization of styrene. In this transformation, methyl radical resulting from dimethyl sulfoxide firstly attacks styrenes to provide alkyl radicals which then undergo alkylation at the C3 position of quinoxalin-2(1H)-one. A green, convenient, and simple protocol for the synthesis of 3-alkylquinoxalin-2(1H)-ones was provided.

Ultraviolet Photodissociation of Gas-Phase Alcohols, Amines, and Nitroalkanes

1996 ◽  
Vol 50 (5) ◽  
pp. 608-613 ◽  
Author(s):  
Philip L. Ross ◽  
Scott E. Van Bramer ◽  
Murray V. Johnston
Keyword(s):  
Vacuum Ultraviolet ◽  
Large Species ◽  
Methyl Radical ◽  
Alkyl Radicals ◽  
Bond Dissociation ◽  
Free Jet ◽  
Flight Mass Spectrometry ◽  
Collisional Cooling ◽  
193 Nm ◽  
Substituted Alkanes

The 193-nm photochemistry of alcohols, amines, and nitroalkanes in the C3-C6 size range is presented. The photolysis products are photoionized with coherent vacuum ultraviolet radiation and analyzed by time-of-flight mass spectrometry. For alcohols and amines, C-C bond dissociation competes with dissociations involving the heteroatom (C-O, O-H, C-N, N-H). Dissociation of the α(C-C) bond is preferred over other locations. Dissociation of a C-C bond is suppressed when a methyl radical would be produced. This behavior is similar to that observed for other substituted alkanes. Nitroalkanes exhibit both C-N and N-O bond dissociation pathways. Their low bond energies cause a substantial amount of internal energy to be partitioned among the primary photodissociation products. Under collision-free conditions, the alkyl radicals produced from these molecules undergo extensive secondary fragmentation. If the photodissociation step is performed in a free jet expansion, collisional cooling stabilizes the primary products and allows large species, such as intact pentyl and hexyl radicals, to be detected.

scholarly journals The polymerization of olefines induced by free radicals

1941 ◽  
Vol 179 (977) ◽  
pp. 169-193 ◽  
Keyword(s):  
Methyl Radical ◽  
Reaction Cycle ◽  
Alkyl Radicals ◽  
Successive Addition ◽  
Rate Of Polymerization ◽  
Alternative Processes ◽  
Complex Polymer ◽  
Ethyl Radicals ◽  
Kinetics Of ◽  
Polymerization Chain

The rate of photolysis of the simple aldehydes at 300° is in general reduced by ethylene, propylene or iso -butylene, and many molecules of the olefine may undergo an induced polymerization for each quantum of light absorbed by the aldehyde. A similar polymerization is induced by photolysis of ketones. The kinetics of these interdependent processes have been investigated by combining pressure measurements with chemical analysis at each stage, the rates of olefine polymerization and of aldehyde photolysis being independently determined. The experimental results accord with a mechanism in which large radicals are built up by the successive addition of olefine molecules to the primary radicals from the photolysis of the aldehyde or ketone. When the polymer radicals contain approximately three olefine molecules they undergo one of two alternative processes, either breaking down by regeneration of a methyl radical which begins a new polymerization chain, or giving inactive products. The former ‘transfer process’ explains how the chain length of the reaction may be large, yet the molecular weight of the product comparatively small. Certain differences between acetaldehyde and propionic aldehyde are explained by the fact that the ethyl radicals from the latter may regenerate in the course of the reaction cycle m ethyl radicals o f slightly greater reactivity. A quantitative comparison o f the various reactions shows that on ascending the series of alkyl radicals their reactivity towards both aldehydes and olefines diminishes only slowly. On ascending the olefine series, how ­ ever, the rate of polymerization rapidly decreases. This depends not upon a lowered efficiency of reaction of the primary radicals with the olefines, but rather upon a greater tendency of the more complex polymer radicals to be transformed into products which do not continue the reaction cycle.

Visible-light-mediated allylation of alkyl radicals with allylic sulfones via a deaminative strategy

2018 ◽  
Vol 5 (23) ◽  
pp. 3443-3446 ◽  
Author(s):  
Miao-Miao Zhang ◽  
Feng Liu
Keyword(s):  
Visible Light ◽  
Visible Light Irradiation ◽  
Bond Formation ◽  
Light Irradiation ◽  
Site Specific ◽  
Alkyl Radicals ◽  
Simple Protocol ◽  
Terminal Alkenes

A mild and simple protocol is developed for the synthesis of terminal alkenes via site-specific C–C bond formation upon visible-light irradiation.

scholarly journals Photoinduced Nickel-Catalyzed Deaminative Cross-Electrophile Coupling

2021 ◽  
Author(s):  
Tao Yang ◽  
Yi Wei ◽  
Ming Joo Koh
Keyword(s):  
Electron Transfer ◽  
Bond Formation ◽  
Cross Coupling ◽  
Alkyl Halides ◽  
Single Electron Transfer ◽  
Alkyl Radicals ◽  
Carbon Carbon Bonds ◽  
Simple Protocol ◽  
Donor Acceptor ◽  
Site Selective

<div>The construction of carbon-carbon bonds through cross-coupling between two electrophiles in the absence of excess metallic reducing agents is a desirable objective in chemistry. Here, we show that <i>N</i>-alkylpyridinium salts can be efficiently merged with aryl or alkyl halides in an intermolecular fashion, affording products in up to 90%</div><div>yield at ambient temperature. These reactions harness the ability of <i>N</i>-alkylpyridinium salts to form electron donor-acceptor complexes with Hantzsch esters, enabling photoinduced single-electron transfer and fragmentation to afford alkyl radicals that are subsequently trapped by a Ni-based catalytic species to promote C(sp<sup>2</sup>)-C(sp<sup>3</sup>) and</div><div>C(sp<sup>3</sup>)-C(sp<sup>3</sup>) bond formation. The operationally simple protocol is applicable to site-selective cross-coupling and tolerates diverse functional groups, including those that are sensitive towards metal reductants.</div>

scholarly journals Spin-trapping with 2-methyl-2-nitrosopropane: photochemistry of carbonyl-containing compounds. Methyl radical formation from dimethyl sulfoxide

1982 ◽  
Vol 60 (12) ◽  
pp. 1486-1492 ◽  
Author(s):  
Ionel Rosenthal ◽  
Magdi M. Mossoba ◽  
Peter Riesz
Keyword(s):  
Dimethyl Sulfoxide ◽  
Hydroxyl Radicals ◽  
Hydrogen Abstraction ◽  
Spin Trapping ◽  
Photochemical Reactions ◽  
Methyl Radicals ◽  
Methyl Radical ◽  
Initial Compound ◽  
Acyl Radical ◽  
Benzyl Radical

The photochemical reactions of several carbonyl-containing compounds investigated by spin-trapping with 2-methyl-2-nitrosopropane revealed different modes of scission depending on the structure of the initial compound. Thus, in photo-Fries rearrangements, the acyl radical was detected. 1,3-Diphenyl-2-propanone decarbonylated to yield the benzyl radical. Finally, valerophenone yielded the radicals expected by γ-hydrogen abstraction. In a dark reaction, dimethyl sulfoxide reacts with NaOH to generate methyl radicals. The latter result suggests the need for caution in the use of dimethyl sulfoxide with 2-methyl-2-nitrosopropane for the detection of hydroxyl radicals.

scholarly journals Selective deoxygenative alkylation of alcohols via photocatalytic domino radical fragmentations

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hong-Mei Guo ◽  
Xuesong Wu
Keyword(s):  
High Reactivity ◽  
Methyl Radical ◽  
Primary Alcohols ◽  
Homolytic Cleavage ◽  
One Pot ◽  
Alkyl Radicals ◽  
Tertiary Alcohols ◽  
Mild Conditions ◽  
Radical Generation ◽  
Selective Formation

AbstractThe delivery of alkyl radicals through photocatalytic deoxygenation of primary alcohols under mild conditions is a so far unmet challenge. In this report, we present a one-pot strategy for deoxygenative Giese reaction of alcohols with electron-deficient alkenes, by using xanthate salts as alcohol-activating groups for radical generation under visible-light photoredox conditions in the presence of triphenylphosphine. The convenient generation of xanthate salts and high reactivity of sequential C–S/C–O bond homolytic cleavage enable efficient deoxygenation of primary, secondary and tertiary alcohols with diverse functionality and structure to generate the corresponding alkyl radicals, including methyl radical. Moreover, chemoselective radical monodeoxygenation of diols is achieved via selective formation of xanthate salts.

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