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.
Synthesis of (E)-α-hydroxyethyl-α,β-unsaturated aldehydes by the reaction of tetrahydrofuran and aromatic aldehydes
Shi, Yong-Sen,Liu, Jian-Feng,Wu, Xiao-Lan,Ke, De-Hong,Xu, Sheng
supporting information, (2021/08/13)
Although α-functionalized α,β-unsaturated aldehydes have important applications in biomedicine, there are few reports on their synthesis. In this article, a new domino reaction for the synthesis of (E)-α-hydroxyethyl-α,β-unsaturated aldehydes was introduced, in which tetrahydrofuran (THF) used as carbonyl block. The first step is an oxidation of THF to 2-hydroxytetrahydrofuran (HTHF) and then it was condensed with ethanolamine under acid catalysis to obtain imine intermediate, which was further isomerized to enamines and used as nucleophiles to attack aldehydes. This is a simple and efficient way for the preparation of (E)-α-hydroxyethyl-α,β-unsaturated aldehydes with notable advantages of a simple procedure, widespread availability of the substrates.
Oxidative Cleavage of Indoles Mediated by Urea Hydrogen Peroxide or H2O2 in Polar Solvents
Llopis, Natalia,Gisbert, Patricia,Baeza, Alejandro
supporting information, p. 3245 - 3249 (2021/06/08)
The oxidative cleavage of indoles (Witkop oxidation) involving the use of H2O2 or urea hydrogen peroxide in combination with a polar solvent has been described. Among these solvents, 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) stands out as the one affording the corresponding 2-ketoacetanilides generally in higher yields The protocol described has also enabled the oxidation of different pyrroles and furans derivatives. Furthermore, the procedure was implemented in a larger-scale and HFIP was distilled from the reaction mixture and reused (up to 4 cycles) without a significant detriment in the reaction outcome, which remarks its sustainability and applicability. (Figure presented.).
