Author
Hiroyuki Kageyama
Bio: Hiroyuki Kageyama is an academic researcher. The author has contributed to research in topics: Quantum yield & Light intensity. The author has an hindex of 1, co-authored 1 publications receiving 33 citations.
Topics: Quantum yield, Light intensity, Intramolecular force
Papers
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TL;DR: A series of 4-substituted 2′-hydroxychalcones underwent photocyclization to give the corresponding flavanones selectively, but in low quantum yields, on visible irradiation in polar aprotic solvents as discussed by the authors.
Abstract: A series of 4-substituted 2′-hydroxychalcones underwent photocyclization to give the corresponding flavanones selectively, but in low quantum yields, on visible irradiation in polar aprotic solvents. Hydroxylic solvents, which disturbed the formation of a cyclic intramolecular hydrogen bond, strongly retarded the photoreaction, while neither triplet quenchers nor free radical inhibitors affected the reaction. The quantum yields were independent of the light intensity, implying a one-photon process, but strongly depended on the wavelength of irradiation. Mechanisms were proposed assuming π, π* excited states and Weller's postulate of a dynamic equilibrium in a proton-transfer double-minimum potential.
35 citations
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TL;DR: This review covers all published synthetic photochemical transformations of the different classes of flavonoids and is the first comprehensive review on the photochemistry of Flavonoids.
Abstract: Flavonoids and their photochemical transformations play an important role in biological processes in nature. Synthetic photochemistry allows access to molecules that cannot be obtained via more conventional methods. This review covers all published synthetic photochemical transformations of the different classes of flavonoids. It is first comprehensive review on the photochemistry of flavonoids.
127 citations
TL;DR: Chalcone derivatives are proposed as novel photoinitiators for polymerization upon exposure to visible light (even under soft irradiation conditions: blue LED bulb at 462 nm, halogen lamp, and sunlight) as discussed by the authors.
73 citations
TL;DR: In this paper, the authors investigated the possibility of using camphorsulfonic acid as chiral Bronsted acid catalysts for asymmetric cyclization of 2-hydroxychalcones to flavanones.
68 citations
TL;DR: L-Proline is utilized as an efficient organocatalyst for the synthesis of substituted flavanones and chalcones in good yields as mentioned in this paper, which is proved with a variety of substrates ranging from electron-deficient to electron-rich aryl aldehydes and 2-hydroxyacetophenones.
68 citations
TL;DR: A series of benzothiazepines synthesized from the corresponding chalcones have been evaluated as DPPH free‐radical scavengers and as inhibitors of cholinesterases, urease, and α‐glucosidase.
Abstract: A series of 2,4-diaryl-2,3,4,5-tetrahydro- (36-40) and 2,4-diaryl-2,3-dihydro-1,5-benzothiazepines (25-35) have been synthesized from the corresponding chalcones 1-24. Both the benzothiazepines and chalcones were evaluated as DPPH free-radical scavengers and as inhibitors of cholinesterases, urease, and alpha-glucosidase. Compounds 2, 5, 6, 7, 10, 13, 18, 21, 36a, 37a, 37b, and 39a showed significant cholinesterase inhibiting activities. Among the 15 dihydro-1,5-benzothiazepines, 26, 32, and 35 exhibited significant radical-scavenging activities; and six tetrahydro-1,5-benzothiazepines (35, 36a, 36b, 37a, 37b, and 39a) were found to be inhibitors of AChE and BChE. Compounds 22, 25, 26, 33, 35, 36a, 37b, and 39a inhibited urease, and 25 and 27-31 were found to be potent inhibitors of alpha-glucosidase.
66 citations