Direct Synthesis of Enones by Visible-Light-Promoted Oxygenation of Trisubstituted Olefins Using Molecular Oxygen

Synlett ◽  
2020 ◽  
Vol 31 (14) ◽  
pp. 1372-1377
Author(s):  
Shinji Harada ◽  
Daiki Matsuda ◽  
Takahiro Morikawa ◽  
Atsushi Nishida
Keyword(s):  
Visible Light ◽  
Molecular Oxygen ◽  
Active Oxygen Species ◽  
Direct Synthesis ◽  
Reaction System ◽  
Active Oxygen ◽  
Oxygen Species ◽  
Mechanistic Studies ◽  
Trisubstituted Olefins ◽  
One Step

A one-step synthesis of enones from olefins is described. The reaction was performed under visible-light irradiation in the presence of molecular oxygen and a photocatalyst. The reaction proceeded with various types of trisubstituted olefins to give enones in good yields with high regioselectivity. In particular, oxygen- and nitrogen-containing functional groups, heteroaromatic rings, and cyclopropanes were tolerated. Mechanistic studies and previous reports indicated that the active oxygen species generated in the reaction system is singlet oxygen.

scholarly journals Chemiluminescent Detection of Active Oxygen Species, Singlet Molecular Oxygen and Superoxide, Using Cypridina Luciferin Analogues.

1991 ◽  
Vol 57 (9) ◽  
pp. 1711-1715 ◽  
Author(s):  
Nobutaka Suzuki ◽  
Kazue Ogawa ◽  
Binkoh Yoda ◽  
Tateo Nomoto ◽  
Humio Inaba ◽  
...  
Keyword(s):  
Molecular Oxygen ◽  
Active Oxygen Species ◽  
Active Oxygen ◽  
Oxygen Species ◽  
Singlet Molecular Oxygen ◽  
Chemiluminescent Detection

scholarly journals Fine cubic Cu2O nanocrystals as highly selective catalyst for propylene epoxidation with molecular oxygen

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Wei Xiong ◽  
Xiang-Kui Gu ◽  
Zhenhua Zhang ◽  
Peng Chai ◽  
Yijing Zang ◽  
...  
Keyword(s):  
Molecular Oxygen ◽  
Partial Oxidation ◽  
Propylene Oxide ◽  
High Selectivity ◽  
Active Oxygen Species ◽  
Active Oxygen ◽  
Lattice Oxygen ◽  
Oxygen Species ◽  
Propylene Epoxidation ◽  
Selective Catalyst

AbstractPropylene epoxidation with O2 to propylene oxide is a very valuable reaction but remains as a long-standing challenge due to unavailable efficient catalysts with high selectivity. Herein, we successfully explore 27 nm-sized cubic Cu2O nanocrystals enclosed with {100} faces and {110} edges as a highly selective catalyst for propylene epoxidation with O2, which acquires propylene oxide selectivity of more than 80% at 90–110 °C. Propylene epoxidation with weakly-adsorbed O2 species at the {110} edge sites exhibits a low barrier and is the dominant reaction occurring at low reaction temperatures, leading to the high propylene oxide selectivity. Such a weakly-adsorbed O2 species is not stable at high reaction temperatures, and the surface lattice oxygen species becomes the active oxygen species to participate in propylene epoxidation to propylene oxide and propylene partial oxidation to acrolein at the {110} edge sites and propylene combustion to CO2 at the {100} face sites, which all exhibit high barriers and result in decreased propylene oxide selectivity.

Characterization and functional properties of new everbearing strawberry (Fragaria x ananasa Duch.) cultivar, ‘Summertiara’ berries

2014 ◽  
Vol 4 (1) ◽  
pp. 1 ◽  
Author(s):  
Takeshi Nagai ◽  
Misuzu Tamai ◽  
Masato Sato ◽  
Yasuhiro Tanoue ◽  
Norihisa Kai ◽  
...  
Keyword(s):  
Vitamin C ◽  
Sensory Evaluation ◽  
Functional Properties ◽  
Active Oxygen Species ◽  
Active Oxygen ◽  
Antihypertensive Activity ◽  
Oxygen Species ◽  
Total Anthocyanins ◽  
Strawberry Cultivar ◽  
The Stability

Background: In recent years, a new everbearing strawberry cultivar, ‘Summertiara’ was cultivated to supply the strawberries in pre-harvest season from July to October in Japan. For highly research and development of processing of this cultivar, ‘Summertiara’ berries, the objective of this study was to characterize these berries, with relation to chemical parameters, total phenols, total flavonoids, total vitamin C, and total anthocyanins, and was to investigate the solubility and the stability of anthocyanins from the berries. Moreover, the functional properties such as antioxidative activity, active oxygen species scavenging activity, and antihypertensive activity were also evaluated.Methods: Chemical analysis, colour measurement, and sensory evaluation of new everbearing strawberry cultivar, ‘Summertiara’ berries were performed. Next, the solubility of anthocyanins from the berries and stability of these against pH, temperature, and an incandescent lighting were investigated. Moreover, functional properties of the extracts prepared from berries were elucidated using 5 different methods.Results: The contents of water, proteins, lipids, carbohydrates, and ash were the same as those of other cultivar berries. The sugar-acid ratio in the berries was low; these were acidulous. By sensory evaluation, the main factors were vivid red colour, aroma, and acidity. The berries were rich in phenols, flavonoids, vitamin C, and anthocyanins. The anthocyanins of the berries became unstable by heat treatment and light exposures such as visible rays. On the other hand, the extracts prepared from the berries showed the functionalities such as antioxidant activity, active oxygen species scavenging activities, and antihypertensive activity.  Conclusions: The strawberry cultivar, ‘Summertiara’ berries were the most suitable for processing ingredient of strawberry-derived products with superior health promoting functionalities.Keywords: Summertiara, everbearing strawberry cultivar, characterization, sensory evaluation, color and storage, functional property

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