- Dark singlet oxygenation of β-citronellol: A key step in the manufacture of rose oxide
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We describe the development of a scalable process for the "dark" singlet oxygenation of β-citronellol as a key step in the manufacture of the fragrance compound, rose oxide. This process, based on catalytic disproportionation of hydrogen peroxide into singlet oxygen and water, has been carried out on production scale in 10 m3 reactors.
- Alsters, Paul L.,Jary, Walther,Nardello-Rataj, Veronique,Aubry, Jean-Marie
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- Unusual Oxidative Dealkylation Strategy toward Functionalized Phenalenones as Singlet Oxygen Photosensitizers and Photophysical Studies
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A series of functionalized 6-alkoxy phenalenones was prepared through an unprecedented oxidative dealkylation of readily available phenalene precursors. The starting phenalenes were efficiently synthesized via an aminocatalyzed annulation/O-alkylation str
- De Bonfils, Paul,Verron, Elise,Sandoval-Altamirano, Catalina,Jaque, Pablo,Moreau, Xavier,Gunther, German,Nun, Pierrick,Coeffard, Vincent
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p. 10603 - 10616
(2020/09/23)
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- “Dark” Singlet Oxygen Made Easy
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An operationally simple continuous flow generator of “dark” singlet oxygen has been developed. The singlet oxygen was efficiently reacted with several chemical traps to give the corresponding oxygenated products in high yields. The developed “dark” singlet oxygen generator has been successfully applied in the synthesis of the antimalarial drug artemisinin.
- Elsherbini, Mohamed,Allemann, Rudolf K.,Wirth, Thomas
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supporting information
p. 12486 - 12490
(2019/08/26)
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- A biocatalytic route towards rose oxide using chloroperoxidase
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The chiral monoterpene alcohol citronellol was converted to the corresponding bromohydrin by the haem-thiolate enzyme chloroperoxidase (CPO) from Caldariomyces fumago in the presence of hydrogen peroxide and bromide ions. A conversion rate of 51% could be achieved under adapted reaction conditions, which easily yield product in the gramme per litre range while only needing catalytic amounts of enzyme. The bromohydroxylation was shown to be highly regioselective yielding 6-bromo-3,7-dimethyloctane-1,7-diol as the sole product. Product identity was confirmed by GC-MS, 1H- and 13C-NMR spectroscopy and the synthesis of reference compounds. However, the reaction was shown to be non-stereospecific because enantiopure (R)- and (S)-citronellol, respectively, gave 1:1-diasteromeric mixtures of the corresponding bromohydrins. A racemic mixture of (R/S)-citronellol was bromohydroxylated without any detectable enantiodiscrimination. The total lack of stereospecificity and enantiodiscrimination points to a reaction mechanism where the oxidised bromide intermediate is not a ligand to the Fe(III)-haem at the distal site but is released from the enzyme active site. The final bromide transfer occurs probably outside the active site via a diffusible oxidised bromide species and the demonstrated regioselectivity is purely chemically controlled. The generated bromohydrins can be straightforward converted via two reactions steps into rose oxide which is a highly valuable flavour and fragrance substance.
- Piantini, Umberto,Schrader, Jens,Wawrzun, Andrzej,Wüst, Matthias
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p. 1025 - 1029
(2012/06/01)
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- Highly efficient continuous flow reactions using singlet oxygen as a "Green" reagent
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Described is a new method for the efficient in situ production of singlet oxygen in a simple continuous flow photochemical reactor. The extremely large interfacial area generated by running the biphasic mixture in a narrow channel at a high flow rate ensures high throughput as well as fast and efficient oxidation of various alkenes, 1,3-dienes, and thioethers on a preparative scale.
- Levesque, Francois,Seeberger, Peter H.
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supporting information; experimental part
p. 5008 - 5011
(2011/12/04)
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- PROCESS FOR THE OXIDATION OF ORGANIC SUBSTRATES BY MEANS OF SINGLET OXYGEN AT HIGH REACTION TEMPERATURES
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Process for the oxidation of organic substrates by means of singlet oxygen, in which organic substrates which react with 1O2 are admixed with 10-70% strength H2O2 in an organic solvent in the presence of a molybdenum-based catalyst at a pH of 9 - 14 and a temperature in the range from 500C to the reflux temperature, whereupon the oxidation to the corresponding oxidation products occurs subsequent to the catalytic decomposition of H2O2 into water and 1O2.
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Page/Page column 7-8; 10
(2008/06/13)
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