5371-52-8Relevant academic research and scientific papers
Dioxygen activation by siloxide complexes of chromium(II) and chromium(IV)
Schax, Fabian,Bill, Eckhard,Herwig, Christian,Limberg, Christian
, p. 12741 - 12745 (2014)
The reaction of a tripodal trisilanol with n-butyllithium and CrCl2 results in a dinuclear CrII complex (1), which is capable of cleaving O2 to yield in a unique complex (2) with an asymmetric diamond core composed of two CrIV=O units. Magnetic susceptibility data reveal significant exchange coupling of CrII (S=2) in 1 and large zero-field splitting for CrIV (S=1) in 2 owing to strong spin-orbit coupling of the ground state. The CrIV=O compound can also be generated using PhIO, and evidence was gathered that although it is the stable product isolated after excessive O2 treatment, it further activates O2 to yield an intermediate species that oxidizes THF or Me-THF. By extensive 18O labeling studies we were able to show, that in the course of this process 18O2 exchanges its label with siloxide O atoms of the ligand via terminal oxido ligands.
Oxidation of tetrahydrofuran to butyrolactone catalyzed by iron-containing clay
Ausavasukhi, Artit,Sooknoi, Tawan
, p. 435 - 441 (2015)
Thermally treated iron-containing clay was used as a greener oxidation catalyst for the conversion of tetrahydrofuran (THF) to butyrolactone (BTL). Mild liquid phase reactions were tested at 50-66 °C using hydrogen peroxide (H2O2) as an oxidizing agent. XRD, TGA, ESR, DR-UV, and FTIR revealed the dislodged iron oxide species formed by treating at ≥500 °C. Formation of active oxidizing species on the surface occurs on contact the dislodged Fe(III) oxide with H2O2. Such active species can promote the oxidation of THF, giving high yield and selectivity of BTL, whereas the iron-containing clay treated at lower temperatures (2O2/THF ratio of 1.0 is sufficient for the production of BTL. Deactivation can be observed presumably due to deposition of the products despite slight leaching of the active iron species.
Synthesis of functionalized bicyclic imines via intramolecular azide-alkene 1,3-dipolar cycloaddition/intramolecular stork alkylation cascade reaction
De Miguel, Irene,Velado, Marina,Herradon, Bernardo,Mann, Enrique
, p. 1237 - 1242 (2013)
A cascade intramolecular azide-alkene 1,3-dipolar cycloaddition/Stork alkylation reaction has been developed for the synthesis of functionalized cyclic imines with a pyrroline and piperideine structures, employing readily available ω-azidodienes. Copyright
Synthetic studies of ingenol: Synthesis of in,out- tricyclo[7.4.1.01,5]tetradecan-14-one
Kigoshi, Hideo,Suzuki, Yuto,Aoki, Kenta,Uemura, Daisuke
, p. 3927 - 3930 (2000)
in,out-Tricyclo[7.4.1.01,5]tetradecan-14-one was synthesized from γ- butyrolactone in 12 steps using ring-closing olefin metathesis as the key step. (C) 2000 Elsevier Science Ltd.
Genotoxicity screening for N-nitroso compounds. Electrochemical and electrochemiluminescent detection of human enzyme-generated DNA damage from N-nitrosopyrrolidine
Krishnan, Sadagopan,Hvastkovs, Eli G.,Bajrami, Besnik,Jansson, Ingela,Schenkman, John B.,Rusling, James F.
, p. 1713 - 1715 (2007)
We report for the first time voltammetric/electrochemiluminescent sensors applied to predict genotoxicity of N-nitroso compounds bioactivated by human cytochrome P450 enzymes. The Royal Society of Chemistry.
Formal synthesis of optically active ingenol via ring-closing olefin metathesis
Watanabe, Kazushi,Suzuki, Yuto,Aoki, Kenta,Sakakura, Akira,Suenaga, Kiyotake,Kigoshi, Hideo
, p. 7802 - 7808 (2004)
The construction of strained carbon skeletons by ring-closing olefin metathesis (RCM) was investigated. With well-designed diene 4, RCM was found to be applicable to the formation of a highly strained inside-outside bicyclo[4.4.1]undecane skeleton of ingenol, a bioactive diterpenoid, and formal total synthesis of optically active ingenol (1) was achieved. The key features of this synthesis are construction of an A-ring by spirocyclization of the ketone with an allylic chloride unit, 26, and ring closure of a B-ring by olefin metathesis. Starting from Funk's keto ester 6, the key intermediate aldehyde 9 in Winkler's total synthesis was synthesized in eight steps in 12.5% overall yield. This strategy of direct cyclization of a strained inside-outside skeleton provided the first easy access to optically active ingenol.
Free-radical approaches to stemoamide and analogues
Bogliotti, Nicolas,Dalko, Peter I.,Cossy, Janine
, p. 9528 - 9531 (2006)
(Chemical Equation Presented) Two approaches allowing access to the tricyclic stemona backbone are presented. Both approaches rely on a free-radical cyclization reaction as the key step. In the formal synthesis of (±)-stemoamide, the construction of the A ring of the natural product was achieved via a 5-exo-trig radical cyclization with atom transfer. The two diastereoisomers issuing from this cyclization showed different reactivity while forming the seven-membered ring of the final product. In the second part of this study, a 1-exo-trig free radical cyclization was realized allowing access to the (±)-9,10-bis-epi-stemoamide. This reaction was highly stereoselective and allowed the control of three of the four contiguous stereocenters present in the molecule.
Catalytic behaviour of the Cu(I)/L/TEMPO system for aerobic oxidation of alcohols - a kinetic and predictive model
Abu-Radaha, Batool,Al-Hunaiti, Afnan,Repo, Timo,Wraith, Darren
, p. 7864 - 7871 (2022/04/09)
Here, we disclose a new copper(i)-Schiff base complex series for selective oxidation of primary alcohols to aldehydes under benign conditions. The catalytic protocol involves 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), N-methylimidazole (NMI), ambient air, acetonitrile, and room temperature. This system provides a straightforward and rapid pathway to a series of Schiff bases, particularly, the copper(i) complexes bearing the substituted (furan-2-yl)imine bases N-(4-fluorophenyl)-1-(furan-2-yl)methanimine (L2) and N-(2-fluoro-4-nitrophenyl)-1-(furan-2-yl)methanimine (L4) have shown excellent yields. Both benzylic and aliphatic alcohols were converted to aldehydes selectively with 99% yield (in 1-2 h) and 96% yield (in 16 h). The mechanistic studies via kinetic analysis of all components demonstrate that the ligand type plays a key role in reaction rate. The basicity of the ligand increases the electron density of the metal center, which leads to higher oxidation reactivity. The Hammett plot shows that the key step does not involve H-abstraction. Additionally, a generalized additive model (GAM, including random effect) showed that it was possible to correlate reaction composition with catalytic activity, ligand structure, and substrate behavior. This can be developed in the form of a predictive model bearing in mind numerous reactions to be performed or in order to produce a massive data-set of this type of oxidation reaction. The predictive model will act as a useful tool towards understanding the key steps in catalytic oxidation through dimensional optimization while reducing the screening of statistically poor active catalysis.
Dual C(sp3)-H Functionalization of Cyclic Ethers via Singlet Oxygen-Mediated Ring Opening and Ring Closing
Yuan, Xu,Yu, Xianglin,He, Kun,Zhang, Ruihan,Xiao, Weilie,Lin, Jun,Zhan, Zhajun,Cheng, Xiaohong,Shao, Zhihui,Jin, Yi
supporting information, p. 8267 - 8272 (2021/10/25)
A metal-free dual C(sp3)-H bond functionalization of saturated cyclic ethers via photooxidative singlet oxygen-mediated ring opening and ring closing has been developed, providing a method for generating hydrobenzofurans/pyrans/dioxins. Mechanistic studies have confirmed that ring-opening intermediates were effectively generated by singlet oxygen-mediated C(sp3)-H activation and efficiently reacted with aldehydes and activated methylene compounds to form a wide array of products with high diastereoselectivities (up to >95:5 dr). This study is a rare example of α,β-dual C(sp3)-H bond functionalization of ethers.
Visible light-induced Minisci reaction through photoexcitation of surface Ti-peroxo species
Naniwa, Shimpei,Yamamoto, Akira,Yoshida, Hisao
, p. 3376 - 3384 (2021/06/06)
Photocatalytic Minisci-type functionalization of pyridine with tetrahydrofuran (THF) proceeded using hydrogen peroxide (H2O2) and a TiO2photocatalyst under acidic conditions. Under UV light (λ= 360 nm), the reaction selectivity based on pyridine (Spy) was >99% while the selectivity based on THF (STHF) was low such as 19%. In contrast, under visible light (λ= 400 or 420 nm)Spywas similarly high (>99%) andSTHFwas two times higher than that under UV light. A surface peroxo complex formed upon contact of hydrogen peroxide with the TiO2surface can be selectively photoexcited by visible light to inject the photoexcited electron to the conduction band of TiO2. The electron can reduce H2O2to a reactive oxygen species (ROS) and promote selectively the Minisci-type cross-coupling reaction between pyridinium ions and THF. A reaction test with a hole scavenger (methanol) evidenced that the hole oxidation of H2O2under UV light is responsible for the lower selectivity, in other words, the higher selectivity under visible light would be due to suppression of the hole oxidation of H2O2. These results demonstrate a novel way to improve the selectivity of the photocatalytic cross-coupling reaction by using H2O2as an oxidant with the photoexcitation of surface Ti-peroxo species on TiO2
