502-42-1Relevant articles and documents
Green, selective and swift oxidation of cyclic alcohols to corresponding ketones
Chatel, Gregory,Monnier, Camille,Kardos, Nathalie,Voiron, Celine,Andrioletti, Bruno,Draye, Micheline
, p. 157 - 164 (2014)
Cyclohexanol oxidation to cyclohexanone is an important reaction in both organic chemistry and industry. We propose here an efficient, eco-friendly, and general method for oxidizing five- to eight-membered cyclanols used as model substrates, with aqueous hydrogen peroxide (H2O2) in the presence of tungstic acid (H2WO4) as a catalyst and an ammonium-based ionic liquid (IL) as a co-catalyst under organic solvent-free conditions. Cyclohexanol was found to be the most reactive of the four tested cyclanols. In addition, the role of the IL as a phase transfer catalyst was confirmed by the use of Aliquat 336 and the kinetic of the reaction was significantly improved under microwave or ultrasonic activation, leading to excellent yields in only a few minutes.
A new property of geminal bishydroperoxides: Hydrolysis with the removal of hydroperoxide groups to form a ketone
Terent'ev,Krivykh,Krylov,Ogibin, Yu. N.,Nikishin
, p. 1667 - 1671 (2010)
A new property of geminal bishydroperoxide was discovered: the ability to hydrolyze in acid medium in the presence of hydrogen peroxide with the formation of ketones. The most resistant to hydrolysis are the cyclic C 6-bishydroperoxydes: at room temperature within one day they are practically not hydrolyzed; less stable is bishydroperoxycycloheptane (C 7): in a day its one fifth part is hydrolyzed. Bishydroperoxydes with the cycles of C8 and C12 for the same time hydrolyzed to 80 and 90% respectively. Of the two linear bishydroperoxydes, 2,2-dihydroperoxydecane, with sterically unhindered center, is more resistant to hydrolysis than 6,6-dihydroperoxyundecane. Pleiades Publishing, Ltd., 2010.
Lown
, p. 3294,3296 (1965)
Facile ring opening of siloxy cyclopropanes by photoinduced electron transfer. A new way to β-keto radicals
Rinderhagen, Heiko,Waske, Prashant A.,Mattay, Jochen
, p. 6589 - 6593 (2006)
Siloxy cyclopropanes undergo ring opening and fragmentation of formal silyl cations under formation of β-keto radicals. These reactive intermediates can be used in inter- and intramolecular addition reactions leading to complex ring systems if more than one unsaturated side chain is present in the starting material. Beside some synthetic examples mainly the mechanism will be discussed focusing on the structure of the primarily formed radical cations, the regioselectivity of cyclopropane cleavage (endo vs exo ring opening), leaving of the silyl group, and termination by H-transfer.
An Engineered Cholesterol Oxidase Catalyses Enantioselective Oxidation of Non-steroidal Secondary Alcohols
Heath, Rachel S.,Sangster, Jack J.,Turner, Nicholas J.
, (2022/02/25)
The enantioselective oxidation of 2° alcohols to ketones is an important reaction in synthetic chemistry, especially if it can be achieved using O2-driven alcohol oxidases under mild reaction conditions. However to date, oxidation of secondary alcohols using alcohol oxidases has focused on activated benzylic or allylic substrates, with unactivated secondary alcohols showing poor activity. Here we show that cholesterol oxidase (EC 1.1.3.6) could be engineered for activity towards a range of aliphatic, cyclic, acyclic, allylic and benzylic secondary alcohols. Additionally, since the variants demonstrated high (S)-selectivity, deracemisation reactions were performed in the presence of ammonia borane to obtain enantiopure (R)-alcohols.
Cu6- And Cu8-Cage Sil- And Germsesquioxanes: Synthetic and Structural Features, Oxidative Rearrangements, and Catalytic Activity
Astakhov, Grigorii S.,Levitsky, Mikhail M.,Zubavichus, Yan V.,Khrustalev, Victor N.,Titov, Aleksei A.,Dorovatovskii, Pavel V.,Smol'Yakov, Alexander F.,Shubina, Elena S.,Kirillova, Marina V.,Kirillov, Alexander M.,Bilyachenko, Alexey N.
, p. 8062 - 8074 (2021/05/26)
This study reports intriguing features in the self-assembly of cage copper(II) silsesquioxanes in the presence of air. Despite the wide variation of solvates used, a series of prismatic hexanuclear Cu6 cages (1-5) were assembled under mild conditions. In turn, syntheses at higher temperatures are accompanied by side reactions, leading to the oxidation of solvates (methanol, 1-butanol, and tetrahydrofuran). The oxidized solvent derivatives then specifically participate in the formation of copper silsesquioxane cages, allowing the isolation of several unusual Cu8-based (6 and 7) and Cu6-based (8) complexes. When 1,4-dioxane was applied as a reaction medium, deep rearrangements occurred (with a total elimination of silsesquioxane ligands), causing the formation of mononuclear copper(II) compounds bearing oxidized dioxane fragments (9 and 11) or a formate-driven 1D coordination polymer (10). Finally, a "directed"self-assembly of sil- and germsesquioxanes from copper acetate (or formate) resulted in the corresponding acetate (or formate) containing Cu6 cages (12 and 13) that were isolated in high yields. The structures of all of the products 1-13 were established by single-crystal X-ray diffraction, mainly based on the use of synchrotron radiation. Moreover, the catalytic activity of compounds 12 and 13 was evaluated toward the mild homogeneous oxidation of C5-C8 cycloalkanes with hydrogen peroxide to form a mixture of the corresponding cyclic alcohols and ketones.
Time-Dependent Self-Assembly of Copper(II) Coordination Polymers and Tetranuclear Rings: Catalysts for Oxidative Functionalization of Saturated Hydrocarbons
Costa, Ines F. M.,Kirillova, Marina V.,André, Vania,Fernandes, Tiago A.,Kirillov, Alexander M.
supporting information, p. 14491 - 14503 (2021/07/19)
This study describes a time-dependent self-assembly generation of new copper(II) coordination compounds from an aqueous-medium reaction mixture composed of copper(II) nitrate, H3bes biobuffer (N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid), ammonium hydroxide, and benzenecarboxylic acid, namely, 4-methoxybenzoic (Hfmba) or 4-chlorobenzoic (Hfcba) acid. Two products were isolated from each reaction, namely, 1D coordination polymers [Cu3(μ3-OH)2(μ-fmba)2(fmba)2(H2O)2]n (1) or [Cu2(μ-OH)2(μ-fcba)2]n (2) and discrete tetracopper(II) rings [Cu4(μ-Hbes)3(μ-H2bes)(μ-fmba)]·2H2O (3) or [Cu4(μ-Hbes)3(μ-H2bes)(μ-fcba)]·4H2O (4), respectively. These four compounds were obtained as microcrystalline air-stable solids and characterized by standard methods, including the single-crystal X-ray diffraction. The structures of 1 and 2 feature distinct types of metal-organic chains driven by the μ3- or μ-OH- ligands along with the μ-benzenecarboxylate linkers. The structures of 3 and 4 disclose the chairlike Cu4 rings assembled from four μ-bridging and chelating aminoalcoholate ligands along with μ-benzenecarboxylate moieties playing a core-stabilizing role. Catalytic activity of 1-4 was investigated in two model reactions, namely, (a) the mild oxidation of saturated hydrocarbons with hydrogen peroxide to form alcohols and ketones and (b) the mild carboxylation of alkanes with carbon monoxide, water, and peroxodisulfate to generate carboxylic acids. Cyclohexane and propane were used as model cyclic and gaseous alkanes, while the substrate scope also included cyclopentane, cycloheptane, and cyclooctane. Different reaction parameters were investigated, including an effect of the acid cocatalyst and various selectivity parameters. The obtained total product yields (up to 34% based on C3H8 or up to 47% based on C6H12) in the carboxylation of propane and cyclohexane are remarkable taking into account an inertness of these saturated hydrocarbons and low reaction temperatures (50-60 °C). Apart from notable catalytic activity, this study showcases a novel time-dependent synthetic strategy for the self-assembly of two different Cu(II) compounds from the same reaction mixture.
