Ynonylation of Acyl Radicals by Electroinduced Homolysis of 4-Acyl-1,4-dihydropyridines

2021 ◽  
Author(s):  
Xiaosheng Luo ◽  
Ping Wang
Keyword(s):  
Acyl Radicals

Generation of Phosphoranyl Radicals via Photoredox Catalysis Enables Voltage–Independent Activation of Strong C–O Bonds

2018 ◽  
Author(s):  
Erin Stache ◽  
Alyssa B. Ertel ◽  
Tomislav Rovis ◽  
Abigail G. Doyle
Keyword(s):  
Carboxylic Acids ◽  
Functional Groups ◽  
Single Step ◽  
Direct Access ◽  
Photoredox Catalysis ◽  
Acyl Radical ◽  
Synthetic Strategy ◽  
Acyl Radicals ◽  
Benzyl Radicals ◽  
Aliphatic Carboxylic Acids

Alcohols and carboxylic acids are ubiquitous functional groups found in organic molecules that could serve as radical precursors, but C–O bonds remain difficult to activate. We report a synthetic strategy for direct access to both alkyl and acyl radicals from these ubiquitous functional groups via photoredox catalysis. This method exploits the unique reactivity of phosphoranyl radicals, generated from a polar/SET crossover between a phosphine radical cation and an oxygen centered nucleophile. We first show the desired reactivity in the reduction of benzylic alcohols to the corresponding benzyl radicals with terminal H-atom trapping to afford the deoxygenated product. Using the same method, we demonstrate access to synthetically versatile acyl radicals which enables the reduction of aromatic and aliphatic carboxylic acids to the corresponding aldehydes with exceptional chemoselectivity. This protocol also transforms carboxylic acids to heterocycles and cyclic ketones via intramolecular acyl radical cyclizations to forge new C–O, C–N and C–C bonds in a single step.

scholarly journals Selective 6-endo Cyclization of the Acyl Radicals onto the Nitrogen of Imine and Oxazoline C—N Bonds.

ChemInform ◽  
2006 ◽  
Vol 37 (44) ◽  
Author(s):  
Mami Tojino ◽  
Noboru Otsuka ◽  
Takahide Fukuyama ◽  
Hiroshi Matsubara ◽  
Ilhyong Ryu
Keyword(s):  
Acyl Radicals

On the rates of decarbonylation of hydroxyacetyl and other acyl radicals

1986 ◽  
Vol 18 (7) ◽  
pp. 791-800 ◽  
Author(s):  
J. -K. Vollenweider ◽  
H. Paul
Keyword(s):  
Acyl Radicals

scholarly journals Light-Driven Vitamin B12 -Catalysed Generation of Acyl Radicals from 2-S -Pyridyl Thioesters

2017 ◽  
Vol 359 (20) ◽  
pp. 3560-3565 ◽  
Author(s):  
Michał Ociepa ◽  
Oskar Baka ◽  
Jakub Narodowiec ◽  
Dorota Gryko
Keyword(s):  
Vitamin B12 ◽  
Acyl Radicals

scholarly journals DABCO-promoted photocatalytic C–H functionalization of aldehydes

2021 ◽  
Vol 17 ◽  
pp. 2959-2967
Author(s):  
Bruno Maia da Silva Santos ◽  
Mariana dos Santos Dupim ◽  
Cauê Paula de Souza ◽  
Thiago Messias Cardozo ◽  
Fernanda Gadini Finelli
Keyword(s):  
Hydrogen Atom ◽  
Cross Coupling ◽  
Hydrogen Atom Transfer ◽  
Direct Application ◽  
Atom Transfer ◽  
Organic Base ◽  
Aryl Bromides ◽  
Computational Calculations ◽  
Acyl Radicals ◽  
Aryl Ketones

Herein we present a direct application of DABCO, an inexpensive and broadly accessible organic base, as a hydrogen atom transfer (HAT) abstractor in a photocatalytic strategy for aldehyde C–H activation. The acyl radicals generated in this step were arylated with aryl bromides through a well stablished nickel cross-coupling methodology, leading to a variety of interesting aryl ketones in good yields. We also performed computational calculations to shine light in the HAT step energetics and determined an optimized geometry for the transition state, showing that the hydrogen atom transfer between aldehydes and DABCO is a mildly endergonic, yet sufficiently fast step. The same calculations were performed with quinuclidine, for comparison of both catalysts and the differences are discussed.

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