126-21-6Relevant academic research and scientific papers
Ruthenium-Catalyzed Oxidation of Nonactivated Alcohols by MnO2
Karlsson, Ulrika,Wang, Guo-Zhi,Baeckvall, Jan-E.
, p. 1196 - 1198 (1994)
Nonactivated alcohols are oxidized to ketones by MnO2 in the presence of a catalytic system consisting of 2 (1) and 2,6-di-tert-butylbenzoquinone (2).The reaction proceeds via a ruthenium-catalyzed dehydrogenation of the alcohol and subsequent hydrogen transfer to 2,6-di-tert-butylbenzoquinone (2).The hydroquinone formed is reoxidized to quinone by MnO2.
A Structural View on the Stereospecificity of Plant Borneol-Type Dehydrogenases
Chánique, Andrea M.,Dimos, Nicole,Drienovská, Ivana,Calderini, Elia,Pantín, Mónica P.,Helmer, Carl P. O.,Hofer, Michael,Sieber, Volker,Parra, Loreto P.,Loll, Bernhard,Kourist, Robert
, p. 2262 - 2277 (2021)
The development of sustainable processes for the valorization of byproducts and other waste streams remains an ongoing challenge in the field of catalysis. Racemic borneol, isoborneol and camphor are currently produced from α-pinene, a side product from the production of cellulose. The pure enantiomers of these monoterpenoids have numerous applications in cosmetics and act as reagents for asymmetric synthesis, making an enzymatic route for their separation into optically pure enantiomers a desirable goal. Known short-chain borneol-type dehydrogenases (BDHs) from plants and bacteria lack the required specificity, stability or activity for industrial utilization. Prompted by reports on the presence of pure (?)-borneol and (?)-camphor in essential oils from rosemary, we set out to investigate dehydrogenases from the genus Salvia and discovered a dehydrogenase with high specificity (E>120) and high specific activity (>0.02 U mg?1) for borneol and isoborneol. Compared to other specific dehydrogenases, the one reported here shows remarkably higher stability, which was exploited to obtain the first three-dimensional structure of an enantiospecific borneol-type short-chain dehydrogenase. This, together with docking studies, led to the identification of a hydrophobic pocket in the enzyme that plays a crucial role in the stereo discrimination of bornane-type monoterpenoids. The kinetic resolution of borneol and isoborneol can be easily integrated into the existing synthetic route from α-pinene to camphor thereby allowing the facile synthesis of optically pure monoterpenols from an abundant renewable source.
Photochemical Transformations with Iodine Azide after Release from an Ion-Exchange Resin
Dr?ger, Gerald,K?sel, Teresa,Kirschning, Andreas,Schulz, G?ran
supporting information, p. 12376 - 12380 (2020/05/08)
This report discloses the photochemical homolytic cleavage of iodine azide after its formation following release from polymer-bound bisazido iodate(I) anions. A series of radical reactions are reported including the 1,2-functionlization of alkenes and the unprecedented chemoselective oxidation of secondary alcohols in the presence of primary alcohols.
Cobalt(II) Coordination Polymers Assembled from Unexplored Pyridine-Carboxylic Acids: Structural Diversity and Catalytic Oxidation of Alcohols
Gu, Jinzhong,Wen, Min,Cai, Yan,Shi, Zifa,Nesterov, Dmytro S.,Kirillova, Marina V.,Kirillov, Alexander M.
, p. 5875 - 5885 (2019/05/08)
New coordination polymers of cobalt(II), namely, [Co(μ4-cpna)(H2O)2]n (1), [Co(μ3-cpna)(phen)(H2O)]n·nH2O (2), [Co3(μ4-dppa)2(H2O)6]n·2nH2O (3), and [Co3(μ5-dppa)2(μ-4,4-bipy)(H2O)2]n·4nH2O (4), have been generated under hydrothermal conditions from CoCl2·6H2O, two different multifunctional pyridine-carboxylic acids {H2cpna: 5-(4-carboxyphenoxy)nicotinic acid; H3dppa: 5-(3,4-dicarboxylphenyl)picolinic acid}, and optional N,N-supporting ligands {phen: 1,10-phenanthroline; 4,4-bipy: 4,4-bipyridine} acting as mediators of crystallization. These Co(II) coordination polymers (CPs) have been obtained as stable crystalline materials and characterized by conventional solid-state techniques, including X-ray crystallography. The obtained products are 3D metal-organic frameworks (MOFs 1 and 4) or 2D coordination polymers (CPs 2 and 3). Analysis of the topologies of simplified nets has revealed the sra (1), fes (2), and 3,4L13 (3) networks, in addition to a very complex topologically unique framework in 4. An observed diversity of structures is driven by types of carboxylate building blocks and crystallization mediators. Thermal stability and magnetic and catalytic properties of 1-4 have also been studied. In fact, the Co(II) compounds act as heterogeneous catalysts for the oxidation of alcohols with tBuOOH (tert-butylhydroperoxide) under mild conditions. Compound 2 features a good catalytic activity (up to 45% yield) in the oxidation of 1-indanol to 1-indanone. Finally, products 1-4 broaden a still very small number of CPs or MOFs driven by the present type of multifunctional pyridine-carboxylic acids (H2cpna, H2dppa).
Oxidation of secondary alcohols using solid-supported hypervalent iodine catalysts
Ballaschk, Frederic,Kirsch, Stefan F.
supporting information, p. 5896 - 5903 (2019/11/11)
It is shown how secondary alcohols are oxidized to provide the corresponding ketones by use of Oxone and solid-supported hypervalent iodine catalysts. Under experimentally simple conditions with acetonitrile at elevated temperatures, excellent conversions were achieved with low catalyst loadings (0.2-5 mol%) when employing the conjugates 5 and 6 derived from IBX and IBS. The catalysts are broadly applicable to a range of alcohol substrates. Of primary importance with respect to sustainability issues, the metal-free catalysts are easily removed from the reaction mixture through filtration, and they can be re-used in oxidation processes for multiple times, without loss of catalytic activity.
Molybdenum complexes with a μ-O{MoO2}2 core: their synthesis, crystal structure and application as catalysts for the oxidation of bicyclic alcohols using N-based additives
Maurya, Mannar R.,Rana, Lata,Avecilla, Fernando
, p. 724 - 734 (2017/02/05)
Three binuclear μ-oxidobis{dioxidomolybdenum(vi)} complexes, [(μ-O){MoVIO2(MeOH)}2(L1)] 1, [(μ-O){MoVIO2(MeOH)}2(L2)] 2, and [(μ-O){MoVIO2(MeOH)}2(L3)] 3 with potential dibasic tetradentate azine ligands [H2L1 = azine of salicylaldehyde, H2L2 = azine of 3-methoxysalicyaldehyde and H2L3 = azine of 3,5-ditertiarybutylsalicylaldehyde] are reported. The complexes are characterized via elemental analysis, various spectroscopic techniques (FT-IR, UV-Vis, 1H and13C NMR), thermogravimetric analysis and single-crystal X-ray diffraction (2 and 3) studies. These complexes are binuclear having a μ-O{MoO2}2 core where ligands coordinate through a set of phenolic oxygen and azine nitrogen to each molybdenum, thus behaving as bis(bidentate). These complexes are investigated as catalysts for the oxidation of two bicyclic alcohols (fenchyl alcohol and isoborneol) using 30% H2O2 as the oxidant in the presence of NEt3 as the additive. The conversion of bicyclic alcohols within the additives follows the order: NEt3 > py > NH3 > K2CO3 > KOH. In the presence of an N-based additive, fenchyl alcohol and isoborneol selectively give high yields of fenchone and camphor, respectively, while in the absence of the additive the conversion is relatively low.
Secondary Phosphine Oxides as Multitalented Preligands En Route to the Chemoselective Palladium-Catalyzed Oxidation of Alcohols
Vasseur, Alexandre,Membrat, Romain,Gatineau, David,Tenaglia, Alphonse,Nuel, Didier,Giordano, Laurent
, p. 728 - 732 (2017/03/13)
Secondary phosphine oxides O=PHR2 (SPOs) were identified as multitalented preligands for the chemoselective Pd-catalyzed oxidation of alcohols by a hydrogen-abstracting methodology. SPOs were found to promote the hydrogen-abstraction step as well as hydrogen transfer to a Michael acceptor by generating a putative active H?Pd species. The catalytic system operates under neutral conditions and was proven to be compatible with various electrophilic and nucleophilic functionalities within the substrates as well as water- and air-sensitive functional groups.
Copper(ii) and iron(iii) complexes with arylhydrazone of ethyl 2-cyanoacetate or formazan ligands as catalysts for oxidation of alcohols
Martins, Nuno M. R.,Mahmudov, Kamran T.,Guedes Da Silva, M. Fátima C.,Martins, Luísa M. D. R. S.,Pombeiro, Armando J. L.
supporting information, p. 10071 - 10083 (2016/12/07)
The aquasoluble [Cu(1κN,O2:2κO-HL1)(S)]2 [S = CH3OH (1), (CH3)2NCHO (2)] and [Cu(κN-HL1)(en)2]·CH3OH·H2O (3) CuII complexes were prepared by the reaction of CuII nitrate hydrate with the new ligand (E/Z)-4-(2-(1-cyano-2-ethoxy-2-oxoethylidene)hydrazinyl)-3-hydroxybenzoic acid (H3L1), in the presence (for 3) or absence (for 1 and 2) of ethylenediamine (en), while the FeIII complex [Fe(κN3-HL2)2] (4) was isolated by treatment of iron(III) chloride hexahydrate with the new ligand (1E,1E)-N′,2-di(1H-1,2,4-triazol-3-yl)diazenecarbohydrazonoyl cyanide (H3L2), and characterized by elemental analysis, IR spectroscopy and single crystal X-ray diffraction. Cooperative E,Z → E isomerization of H3L1, induced by coordination and ionic interactions, occurs upon interaction with CuII in the presence of en. Complexes 1-4 act as catalyst precursors for the solvent-free microwave (MW) assisted selective oxidation of primary or secondary alcohols and diols to the corresponding aldehydes, ketones and diketones, respectively, with yields in the 5-99% range (TONs up to 4.96 × 102) after 60 min of MW irradiation at 120 °C. The influence of temperature, time and organic radicals was studied and also the regioselective oxidation of the catalytic systems involving the primary and secondary alcohols.
Effect of N-based additive on the optimization of liquid phase oxidation of bicyclic, cyclic and aromatic alcohols catalyzed by dioxidomolybdenum(VI) and oxidoperoxidomolybdenum(VI) complexes
Maurya, Mannar R.,Saini, Neeraj,Avecilla, Fernando
, p. 101076 - 101088 (2015/12/09)
Two dioxidomolybdenum(vi) complexes, [MoVIO2(L1)(MeOH)] (1) and [MoVIO2(L2)(MeOH)] (2) and their corresponding oxidoperoxidomolybdenum(vi) complexes, [MoVIO(O2)(L1)(MeOH)] (3) and [MoVIO(O2)(L2)(MeOH)] (4) with ONO tridentate ligands, 4-[3,5-bis(2-hydroxyphenyl)-1,2,4-triazol-1-yl]benzoic acid (H2L1, I) and 3,5-bis(2-hydroxyphenyl)-1-phenyl-1,2,4-triazole (H2L2, II) have been synthesized and characterized by elemental analysis, spectroscopic techniques (infrared, UV-Vis, 1H and 13C NMR) and thermogravimetric analysis. Structures of 1a (DMSO coordinated) and 2 (methanol coordinated) confirmed by single crystal X-ray study reveal that the tridentate ligands bind to the metal center through two oxygen atoms and a ring nitrogen atom. These complexes have been tested as catalysts for the homogeneous oxidation of bicyclic (isoborneol and fenchyl alcohol), aromatic (benzyl alcohol and cumic alcohol) and cyclic (cyclohexanol) alcohols, using 30% H2O2 as an oxidant. Various parameters such as amounts of catalyst, oxidant, solvent and temperature of the reaction mixture have been taken into consideration for the maximum conversion of substrates. Effect of N-based additive (NEt3) on the conversion of substrates as well as selectivity of the corresponding product(s) under the optimized reaction conditions has also been checked and obtained results suggest that addition of an additive reduces time to achieve equilibrium and increases conversion of alcohols.
Photochemical Oxidation of Thioketones by Singlet Molecular Oxygen Revisited: Insights into Photoproducts, Kinetics, and Reaction Mechanism
Sánchez-Arroyo, Antonio J.,Pardo, Zulay D.,Moreno-Jiménez, Florencio,Herrera, Antonio,Martín, Nazario,García-Fresnadillo, David
, p. 10575 - 10584 (2015/11/18)
Photosensitized oxidation of trimethyl[2.2.1]bicycloheptane thioketones by 1O2 can yield more photoproducts than exclusively ketones and sulfines. Moreover, the ketone/sulfine ratio can be reversed when protic conditions and high thioketone concentrations are used, conversely to earlier results reporting ketones as the main photoproducts. A new mechanistic proposal for sulfine formation is suggested following intermolecular oxygen transfer from a peroxythiocarbonyl intermediate to a second thioketone molecule. Reaction quantum yields (10-5-10-2) depend on the reaction conditions and time. Sulfine production reaches a maximum at short irradiation times, whereas decomposition to the corresponding ketone is observed at long reaction times. When the thioketone substrate has a hydrogen atom at the α position a peroxyvinylsulfenic acid intermediate can be formed by proton transfer. Reaction of this intermediate with another thioketone molecule can yield more sulfine and its tautomeric vinylsulfenic acid, which dimerizes in situ to the thiosulfinate. The hydroperoxyl group of the peroxyvinylsulfenic acid can also rearrange to the α position, and by reaction with the starting thioketone, α-hydroxy thioketone and additional sulfine can be formed, while dehydration yields the α-oxo thioketone. In situ [2 + 2] and [4 + 2] self-cycloaddition of the α-oxo thioketone yields significant amounts of the corresponding adducts at prolonged irradiation times.
