4066-82-4Relevant academic research and scientific papers
Iron(III) Nitrate/TEMPO-Catalyzed Aerobic Alcohol Oxidation: Distinguishing between Serial versus Integrated Redox Cooperativity
Mao, Kaining,Nutting, Jordan E.,Stahl, Shannon S.
supporting information, p. 10565 - 10570 (2021/07/28)
Aerobic alcohol oxidations catalyzed by transition metal salts and aminoxyls are prominent examples of cooperative catalysis. Cu/aminoxyl catalysts have been studied previously and feature "integrated cooperativity", in which CuII and the aminoxyl participate together to mediate alcohol oxidation. Here we investigate a complementary Fe/aminoxyl catalyst system and provide evidence for "serial cooperativity", involving a redox cascade wherein the alcohol is oxidized by an in situ-generated oxoammonium species, which is directly detected in the catalytic reaction mixture by cyclic step chronoamperometry. The mechanistic difference between the Cu- and Fe-based catalysts arises from the use iron(III) nitrate, which initiates a NOx-based redox cycle for oxidation of aminoxyl/hydroxylamine to oxoammonium. The different mechanisms for the Cu- and Fe-based catalyst systems are manifested in different alcohol oxidation chemoselectivity and functional group compatibility.
Ir(NHC)-Catalyzed Synthesis of β-Alkylated Alcohols via Borrowing Hydrogen Strategy: Influence of Bimetallic Structure
Sung, Kihyuk,Lee, Mi-hyun,Cheong, Yeon-Joo,Kim, Yu Kwon,Yu, Sungju,Jang, Hye-Young
supporting information, p. 3090 - 3097 (2021/05/10)
Multi N-heterocyclic carbene(NHC)-modified iridium catalysts were employed in the β-alkylation of alcohols; dimerization of primary alcohols (Guerbet reaction), cross-coupling of secondary and primary alcohols, and intramolecular cyclization of alcohols. Mechanistic studies of Guerbet reaction, including kinetic experiments, mass analysis, and density functional theory (DFT) calculation, were employed to explain the fast reaction promoted by bimetallic catalysts, and the dramatic reactivity increase of monometallic catalysts at the late stage of the reaction. (Figure presented.).
Aryl Boronic Acid Catalysed Dehydrative Substitution of Benzylic Alcohols for C?O Bond Formation
Estopi?á-Durán, Susana,Donnelly, Liam J.,Mclean, Euan B.,Hockin, Bryony M.,Slawin, Alexandra M. Z.,Taylor, James E.
supporting information, p. 3950 - 3956 (2019/02/16)
A combination of pentafluorophenylboronic acid and oxalic acid catalyses the dehydrative substitution of benzylic alcohols with a second alcohol to form new C?O bonds. This method has been applied to the intermolecular substitution of benzylic alcohols to form symmetrical ethers, intramolecular cyclisations of diols to form aryl-substituted tetrahydrofuran and tetrahydropyran derivatives, and intermolecular crossed-etherification reactions between two different alcohols. Mechanistic control experiments have identified a potential catalytic intermediate formed between the aryl boronic acid and oxalic acid.
Sodium Bromide-Catalyzed Oxidation of Secondary Benzylic Alcohols Using Aqueous Hydrogen Peroxide as Terminal Oxidant
Komagawa, Hiromi,Maejima, Yukako,Nagano, Takashi
supporting information, p. 789 - 793 (2016/03/09)
A halide salt, hydroperoxide and AcOH catalyst system was applied to the oxidation of secondary benzylic alcohols. This simple system can be applied to a variety of secondary benzylic alcohols and scaled up for gram-scale preparation. High secondary benzylic alcohol selectivity of the present method is demonstrated in hydroxyketone synthesis. Based on several experimental results, a catalytic cycle for our oxidation is proposed.
Ketyl-type radicals from cyclic and acyclic esters are stabilized by SmI2(H2O)n: the role of SmI2(H 2O)n in post-electron transfer steps
Szostak, Michal,Spain, Malcolm,Procter, David J.
supporting information, p. 8459 - 8466 (2014/06/24)
Mechanistic details pertaining to the SmI2-H2O- mediated reduction and reductive coupling of 6-membered lactones, the first class of simple unactivated carboxylic acid derivatives that had long been thought to lie outside the reducing range of SmI2, have been elucidated. Our results provide new experimental evidence that water enables the productive electron transfer from Sm(II) by stabilization of the radical anion intermediate rather than by solely promoting the first electron transfer as originally proposed. Notably, these studies suggest that all reactions involving the generation of ketyl-type radicals with SmI2 occur under a unified mechanism based on the thermodynamic control of the second electron transfer step, thus providing a blueprint for the development of a broad range of novel chemoselective transformations via open-shell electron pathways.
Highly practical copper(I)/TEMPO catalyst system for chemoselective aerobic oxidation of primary alcohols
Hoover, Jessica M.,Stahl, Shannon S.
supporting information; experimental part, p. 16901 - 16910 (2011/12/04)
Aerobic oxidation reactions have been the focus of considerable attention, but their use in mainstream organic chemistry has been constrained by limitations in their synthetic scope and by practical factors, such as the use of pure O2 as the oxidant or complex catalyst synthesis. Here, we report a new (bpy)CuI/TEMPO catalyst system that enables efficient and selective aerobic oxidation of a broad range of primary alcohols, including allylic, benzylic, and aliphatic derivatives, to the corresponding aldehydes using readily available reagents, at room temperature with ambient air as the oxidant. The catalyst system is compatible with a wide range of functional groups and the high selectivity for 1° alcohols enables selective oxidation of diols that lack protecting groups.
Gold-catalysed cyclic ether formation from diols
Jiang, Xiaolu,London, Emma K.,Morris, David J.,Clarkson, Guy J.,Wills, Martin
experimental part, p. 9828 - 9834 (2011/02/23)
Gold(I) and (III) salts have been found to be highly effective at the catalysis of ether formation from alcohols. Intramolecular ether formation of a 1,5-diol was also achieved, with a stereoselectivity that indicates that an SN1 mechanism predominates. In an attempt to form a seven-membered ring, a stable 14-membered dimer product was also formed. Attempts to control the diastereoselectivity of the reaction using a chiral anionic counterion did not give products with a high de.
TBD-catalyzed direct 5- and 6-enolexo aldolization of ketoaldehydes
Ghobril, Cynthia,Sabot, Cyrille,Mioskowski, Charles,Baati, Rachid
supporting information; experimental part, p. 4104 - 4108 (2009/05/27)
Treatment of unfunctionalized acyclic ketoaldehydes with a catalytic amount of 1,5,7-triazabicyclo[4.4.0]dec-5-ene induces a direct intramolecular 5- and 6-enolexo aldolization, furnishing 2-ketocyclopentanols and 2-ketocyclohexanols in good-to-excellent yields. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
Activated iodosylbenzene monomer as an ozone equivalent: Oxidative cleavage of carbon-carbon double bonds in the presence of water
Miyamoto, Kazunori,Tada, Norihiro,Ochiai, Masahito
, p. 2772 - 2773 (2007/10/03)
Reported here for the first time are the developments of an efficient method for oxidative cleavage of carbon-carbon double bonds yielding carbonyl compounds by using aryl-λ3-iodanes, which involve a combination of iodosylbenzene and HBF4 in the presence of water. The method serves as a safety alternative to ozonolysis. The oxidative cleavage of olefins probably involves the hitherto unknown direct vicinal dihydroxylations of double bonds with aryl-λ3-iodanes and the subsequent oxidative glycol fissions. Cyclic (cyclopentenes, cyclohexenes, etc.) and acyclic olefins are cleaved smoothly under our conditions. In the reaction of electron-deficient styrenes such as m-nitrostyrene, intermediate formation of the corresponding epoxide was detected. A variety of aryloxiranes also undergo an oxidative cleavage of the epoxide rings under our conditions, and aromatic aldehydes were obtained in good yields. Copyright
