36871-91-7Relevant academic research and scientific papers
Cholesterol hydroperoxides generate singlet molecular oxygen [O 2(1Δg)]: Near-IR emission, 18O-labeled hydroperoxides, and mass spectrometry
Uemi, Miriam,Ronsein, Graziella E.,Prado, Fernanda M.,Motta, Flavia D.,Miyamoto, Sayuri,Medeiros, Marisa H. G.,Di Mascio, Paolo
experimental part, p. 887 - 895 (2012/04/11)
In mammalian membranes, cholesterol is concentrated in lipid rafts. The generation of cholesterol hydroperoxides (ChOOHs) and their decomposition products induces various types of cell damage. The decomposition of some organic hydroperoxides into peroxyl
Synthesis of 7-hydroperoxycholesterol and its separation, identification, and quantification in cholesterol heated model systems
Nogueira, Gislaine C.,Costa, Bruna Z.,Crotti, Antonio E. M.,Bragagnolo, Neura
experimental part, p. 10226 - 10230 (2011/05/05)
7-Hydroperoxycholesterol is considered to be an intermediate compound of the cholesterol oxidation path as the first product formed when cholesterol is oxidized by triplet oxygen. However, there is a limitation on cholesterol mechanism studies because of the lack of 7-hydroperoxycholesterol analytical standard due to its low stability. To verify the formation of hydroperoxides in cholesterol model systems heated at 140, 180, and 220 °C, 7α-hydroperoxycholesterol was synthesized by cholesterol photooxidation followed by rearrangement at room temperature in chloroform. Its structure was confirmed on the basis of 13C NMR and mass spectra obtained by APCI-LC-MS. The synthesized compound was also used as standard for the quantification of 7-hydroperoxycholesterol as the sum of 7α-and 7β-hydroperoxycholesterol. The results demonstrated that 7-hydroperoxycholesterol is the first compound formed when the temperature is lower (140 °C). However, the concentration of the 7-hydroperoxycholesterol depends on the temperature and time of exposure: the higher the time, the higher the amount of 7-hydroperoxycholesterol at lower temperatures, and the lower the time, the lower the amount of 7-hydroperoxycholesterol at higher temperatures (180 and 220 °C). By the formation of 7-hydroperoxycholesterol, the known cholesterol oxidation mechanism in three phases (initiation, propagation, and termination) could be confirmed; once at lower temperatures, the stage of cholesterol oxidation is at initiation, at which hydroperoxide formation predominates.
Allylic oxidations catalyzed by dirhodium caprolactamate via aqueous tert-butyl hydroperoxide: The role of the tert-butylperoxy radical
McLaughlin, Emily C.,Choi, Hojae,Wang, Kan,Chiou, Grace,Doyle, Michael P.
supporting information; experimental part, p. 730 - 738 (2009/07/04)
Dirhodium(II) caprolactamate exhibits optimal efficiency for the production of the tert-butylperoxy radical, which is a selective reagent for hydrogen atom abstraction. These oxidation reactions occur with aqueous tert-butyl hydroperoxide (TBHP) without rapid hydrolysis of the caprolactamate ligands on dirhodium. Allylic oxidations of enones yield the corresponding enedione in moderate to high yields, and applications include allylic oxidations of steroidal enones. Although methylene oxidation to a ketone is more effective, methyl oxidation to a carboxylic acid can also be achieved. The superior efficiency of dirhodium(II) caprolactamate as a catalyst for allylic oxidations by TBHP (mol % of catalyst, % conversion) is described in comparative studies with other metal catalysts that are also reported to be effective for allylic oxidations. That different catalysts produce essentially the same mixture of products with the same relative yields suggests that the catalyst is not involved in product-forming steps. Mechanistic implications arising from studies of allylic oxidation with enones provide new insights into factors that control product formation. A previously undisclosed disproportionation pathway, catalyzed by the tert-butoxy radical, of mixed peroxides for the formation of ketone products via allylic oxidation has been uncovered.
Allylic Oxidations Catalyzed by Dirhodium Catalysts under Aqueous Conditions
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Page/Page column 16-18; 20, (2009/04/24)
The present invention relates to compositions and methods for achieving the efficient allylic oxidation of organic molecules, especially olefins and steroids, under aqueous conditions. The invention concerns the use of dirhodium (II,II) “paddlewheel complexes, and in particular, dirhodium carboximate and tert-butyl hydroperoxide as catalysts for the reaction. The use of aqueous conditions is particularly advantageous in the allylic oxidation of 7-keto steroids, which could not be effectively oxidized using anhydrous methods, and in extending allylic oxidation to enamides and enol ethers.
Catalysis of Ene Reactions by Lithium Perchlorate
Davies, Alwyn G.,Kinart, Wojciech J.
, p. 2281 - 2284 (2007/10/02)
The ene reaction of some allylic hydrocarbons, and the metallo-ene reaction of some allyltin compounds, with 1,3,4-triazoline-2,5-diones or with diethyl azodicarboxylate as enophiles, in diethyl ether are strongly catalysed by lithium perchlorate.Azobenzene, on the other hand, reacts slowly with alkyltin compounds, undergoing hydrostannation.The reaction of cholesterol or of tributylallyltin with singlet oxygen is subject to a smaller catalysis.
