Electron-Transfer Reactions of Aromatic alpha,beta-Epoxy Ketones: Factors That Govern Selective Conversion to
Eietsu Hasegawa1, Kenyuki Ishiyama, Takayuki Fujita
1Department of Chemistry, Faculty of Science, Niigata University, Ikarashi, Niigata 950-21, Japan.
Abstract:
Photoreaction of trans-1-(4-cyanophenyl)-3-phenyl-2,3-epoxy-1-propanone (trans-4'-cyanochalcone epoxide) with various electron donors was studied. Irradiation of this epoxy ketone with amines produced 1-(4-cyanophenyl)-3-phenyl-1,3-propanedione and 1-(4-cyanophenyl)-3-hydroxy-3-phenyl-1-propanone in various ratios depending on the kinds of amine and solvent used. A reaction mechanism involving an amine cation radical-assisted rearrangement of the epoxy ketone anion radical was proposed to be most consistent with the marked change in the yield of beta-diketone. On the other hand, the timing of proton transfer to the anionic intermediates is considered to be a key factor to yield the beta-hydroxy ketone. Information obtained from the photochemical study was useful to find the reaction conditions for the conversion of several aromatic epoxy ketones to hydroxy ketones by the use of samarium diiodide. Addition of methanol significantly changed the product distribution. Proper choice of water or methanol as a proton source produced hydroxy ketones in moderate to good yields.
More Related Videos
08:46Regioselective O-Glycosylation of Nucleosides via the Temporary 2',3'-Diol Protection by a Boronic Ester for the Synthesis of Disaccharide Nucleosides
Published on: July 26, 2018
10:18Extraction of Lignin with High β-O-4 Content by Mild Ethanol Extraction and Its Effect on the Depolymerization Yield
Published on: January 7, 2019
Related Concept Videos
E1 Reaction: Stereochemistry and Regiochemistry
Hydroboration-Oxidation of Alkenes
Reactions of Aldehydes and Ketones: Baeyer–Villiger Oxidation
The carbonyl center is activated by...
Intramolecular Claisen Condensation of Dicarboxylic Esters: Dieckmann Cyclization
β-Dicarbonyl Compounds via Crossed Claisen Condensations
Aldol Condensation with β-Diesters: Knoevenagel Condensation
