- Oxidation of alkenes to 1,2-diols: FT-IR and UV studies of silica-supported sulfonic acid catalysts and their interaction with H2O and H 2O2
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Supported sulfonic acids can be employed as efficient catalysts in the dihydroxylation of 1-methylcyclohexene with aqueous hydrogen peroxide, without the use of additional solvents, under mild condition. The reaction was deeply studied in terms of catalys
- Maggi, Raimondo,Martra, Gianmario,Piscopo, Calogero Giancarlo,Alberto, Gabriele,Sartori, Giovanni
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- A Change from Kinetic to Thermodynamic Control Enables trans-Selective Stereochemical Editing of Vicinal Diols
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Here, we report the selective, catalytic isomerization of cis-1,2-diols to trans-diequatorial-1,2-diols. The method employs triphenylsilanethiol (Ph3SiSH) as a catalyst and proceeds under mild conditions in the presence of a photoredox catalyst and under
- Gu, Xin,Wendlandt, Alison E.,Zhang, Yu-An
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supporting information
p. 599 - 605
(2022/01/03)
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- Selective Isomerization via Transient Thermodynamic Control: Dynamic Epimerization of trans to cis Diols
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Traditional approaches to stereoselective synthesis require high levels of enantio- and diastereocontrol in every step that forms a new stereocenter. Here, we report an alternative approach, in which the stereochemistry of organic substrates is selectivel
- Macmillan, David W. C.,Oswood, Christian J.
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supporting information
p. 93 - 98
(2022/01/03)
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- Straightforward Synthesis of Fluorinated Enals via Photocatalytic α-Perfluoroalkenylation of Aldehydes
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(Per)fluorinated substances represent an important compound class with regard to drug design and material chemistry. We found a mild, operationally simple, and inexpensive photocatalytic perfluoroalkenylation reaction giving tetrasubstituted, highly electron-deficient enals straight from aldehydes. This one-step reaction tolerates various functional groups and can be applied to a wide range of substrates giving the products in yields of 52-84%.
- Wulkesch, Christian,Czekelius, Constantin
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p. 7425 - 7438
(2021/06/21)
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- Tandem Lewis acid catalysis for the conversion of alkenes to 1,2-diols in the confined space of bifunctional TiSn-Beta zeolite
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The generation of multifunctional isolated active sites in zeolite supports is an attractive method for integrating multistep sequential reactions into a single-pass tandem catalytic reaction. In this study, bifunctional TiSn-Beta zeolite was prepared by a simple and scalable post-synthesis approach, and it was utilized as an efficient heterogeneous catalyst for the tandem conversion of alkenes to 1,2-diols. The isolated Ti and Sn Lewis acid sites within the TiSn-Beta zeolite can efficiently integrate alkene epoxidation and epoxide hydration in tandem in a zeolite microreactor to achieve one-step conversion of alkenes to 1,2-diols with a high selectivity of >90%. Zeolite confinement effects result in high tandem rates of alkene epoxidation and epoxide hydration as well as high selectivity toward the desired product. Further, the novel method demonstrated herein can be employed to other tandem catalytic reactions for sustainable chemical production.
- Lei, Qifeng,Wang, Chang,Dai, Weili,Wu, Guangjun,Guan, Naijia,Hunger, Michael,Li, Landong
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p. 1176 - 1184
(2021/02/16)
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- Photo-Induced Dihydroxylation of Alkenes with Diacetyl, Oxygen, and Water
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Herein reported is a photo-induced production of vicinal diols from alkenes under mild reaction conditions. The present dihydroxylation method using diacetyl (= butane-2,3-dione), oxygen, and water dispenses with toxic reagents and intractable waste generation.
- Masuda, Yusuke,Ikeshita, Daichi,Murakami, Masahiro
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- Selective palladium nanoparticles-catalyzed hydrogenolysis of industrially targeted epoxides in water
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Palladium nanoparticles, with core sizes of ca. 2.5 nm, were easily synthesized by chemical reduction of Na2PdCl4 in the presence of hydroxyethylammonium salts and proved to be efficient for the selective hydrogenolysis of various aromatic, alkylphenyl, aliphatic epoxides in water as green solvent. Capping agents of the metal species were screened to define the most suitable micellar nanoreactors on two target substrates of industrial interest, epoxystyrene and 7,8-epoxy-2-methoxy-2,6-dimethyloctane. In our conditions, the hydrogenolysis of epoxystyrene proved to be pH-dependent, producing either the diol under acidic conditions, or the sweet-smelling 2-phenylethanol in the presence of a base. Promisingly, 7,8-epoxy-2-methoxy-2,6-dimethyloctane was completely and selectively hydrogenated into Florsantol, a sandalwood odorant at a multigram scale (40 g and up to 175g). A general mechanism for the palladium nanoparticles-catalyzed hydrogenolysis of terminal epoxides was proposed according to steric and electronic properties and finely corroborated with deuterium labelling experiments.
- Duval, Marion,Deboos, Victor,Hallonet, Agnès,Sagorin, Gilles,Denicourt-Nowicki, Audrey,Roucoux, Alain
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p. 261 - 268
(2021/03/22)
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- Liquid-phase oxidation of olefins with rare hydronium ion salt of dinuclear dioxido-vanadium(V) complexes and comparative catalytic studies with analogous copper complexes
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Homogeneous liquid-phase oxidation of a number of aromatic and aliphatic olefins was examined using dinuclear anionic vanadium dioxido complexes [(VO2)2(salLH)]? (1) and [(VO2)2(NsalLH)]? (2) and dinuclear copper complexes [(CuCl)2(salLH)]? (3) and [(CuCl)2(NsalLH)]? (4) (reaction of carbohydrazide with salicylaldehyde and 4-diethylamino salicylaldehyde afforded Schiff-base ligands [salLH4] and [NsalLH4], respectively). Anionic vanadium and copper complexes 1, 2, 3, and 4 were isolated in the form of their hydronium ion salt, which is rare. The molecular structure of the hydronium ion salt of anionic dinuclear vanadium dioxido complex [(VO2)2(salLH)]? (1) was established through single-crystal X-ray analysis. The chemical and structural properties were studied using Fourier transform infrared (FT-IR), ultraviolet–visible (UV–Vis), 1H and 13C nuclear magnetic resonance (NMR), electrospray ionization mass spectrometry (ESI-MS), electron paramagnetic resonance (EPR) spectroscopy, and thermogravimetric analysis (TGA). In the presence of hydrogen peroxide, both dinuclear vanadium dioxido complexes were applied for the oxidation of a series of aromatic and aliphatic alkenes. High catalytic activity and efficiency were achieved using catalysts 1 and 2 in the oxidation of olefins. Alkenes with electron-donating groups make the oxidation processes easy. Thus, in general, aromatic olefins show better substrate conversion in comparison to the aliphatic olefins. Under optimized reaction conditions, both copper catalysts 3 and 4 fail to compete with the activity shown by their vanadium counterparts. Irrespective of olefins, metal (vanadium or copper) complexes of the ligand [salLH4] (I) show better substrate conversion(%) compared with the metal complexes of the ligand [NsalLH4] (II).
- Maurya, Abhishek,Haldar, Chanchal
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- The promotional effect of surface Ru decoration on the catalytic performance of Co-based nanocatalysts for guaiacol hydrodeoxygenation
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In the present work, carbon-supported Ru-decorated Co-based nanocatalysts were fabricated via a layered double hydroxide/carbon composite precursor approach and applied to the efficient hydrodeoxygenation (HDO) of guaiacol to produce cyclohexanol. It was demonstrated that uniform and highly dispersed Co nanoparticles could be formed on the carbon matrix, and the decoration of a small amount of Ru on the surface of Co nanoparticles could introduce stronger hydrogenolysis active sites. Furthermore, the reduction temperature for catalyst precursors could tune the size of Co-containing nanoparticles and regulate the density of surface oxygen vacancies originating from CoOx species. Under the mild reaction conditions (200 ℃ and 1.0 MPa hydrogen pressure), as-fabricated Ru-Co/C catalyst obtained at the reduction temperature of 600 °C showed excellent catalytic activity in the HDO of guaiacol, with a high cyclohexanol yield of ~94 %, which was attributable to surface exposure of highly dispersive Ru° sites and the formation of abundant defective oxygen vacancies. The present results provide a new approach for designing high-performance Co-based HDO nanocatalysts by both the surface decoration of small amounts of precious metals and the introduction of surface defective structures.
- Fan, Guoli,Li, Feng,Shi, Yisheng,Xu, Qiangqiang,Yang, Lan
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- Synthesis method of cyclohexanol derivative 1-methyl-1, 2-cyclohexanediol
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The invention relates to a cyclohexanol derivative 1-methyl-1, 2-cyclohexanediol synthesis method, which comprises: mixing guaiacol and an organic solvent, adding the obtained mixture and a Ni/C catalyst to a reaction kettle, introducing hydrogen gas with a pressure of 1-3 MPa, stirring, and carrying out a heating reaction for 1-3 h at a temperature of 180-260 DEG C; wherein the Ni/C catalyst is anickel-loaded green catalyst taking biomass tar as a carrier. According to the method, synthesis of 1-methyl-1, 2-cyclohexanediol can be achieved in one step, the atom utilization rate reaches 100%,the method has very high conversion rate and selectivity, and the green and energy-saving aims are achieved.
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Paragraph 0033; 0048-0051; 0053-0070
(2020/06/30)
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- Polymer-anchored mononuclear and binuclear CuII Schiff-base complexes: Impact of heterogenization on liquid phase catalytic oxidation of a series of alkenes
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Liquid phase catalytic oxidation of a number of alkenes, for example, cyclohexene, cis-cyclooctene, styrene, 1-methyl cyclohexene and 1-hexene, was performed using polymer-anchored copper (II) complexes PS-[Cu (sal-sch)Cl] (5), PS-[Cu (sal-tch)Cl] (6), PS-[CH2{Cu (sal-sch)Cl}2] (7) and PS-[CH2{Cu (sal-tch)Cl}2] (8). Neat complexes [Cu (sal-sch)Cl] (1), [Cu (sal-tch)Cl] (2), [CH2{Cu (sal-sch)Cl}2] (3) and [CH2{Cu (sal-tch)Cl}2] (4) were isolated by reacting CuCl2·2H2O with [Hsal-sch] (I), [Hsal-tch] (II), [H2bissal-sch] (III) and [H2bissal-tch] (IV), respectively, in refluxing methanol. Complexes 1–4 have been covalently anchored in Merrifield resin through the amine nitrogen of the semicarbazide or thiosemicarbazide moiety. A number of analytical, spectroscopic and thermal techniques, such as CHNS analysis, Fourier transform-infrared, UV–Vis, PMR, 13C-NMR, electron paramagnetic resonance, scanning electron microscopy, energy-dispersive X-ray analysis, thermogravimetric analysis, atomic force microscopy, atomic absorption spectroscopy, and electrospray ionization-mass spectrometry, were used to analyze and establish the molecular structure of the ligands (I)–(IV) and complexes (1)–(8) in solid state as well as in solution state. Grafted complexes 5–8 were employed as active catalysts for the oxidation of a series of alkenes in the presence of hydrogen peroxide. Copper hydroperoxo species ([CuIII (sal-sch)-O-O-H]), which is believed to be the active intermediate, generated during the catalytic oxidation of alkenes, are identified. It was found that supported catalysts are very economical, green and efficient in contrast to their neat complexes as well as most of the recently reported heterogeneous catalysts.
- Maurya, Abhishek,Kesharwani, Neha,Kachhap, Payal,Mishra, Vivek Kumar,Chaudhary, Nikita,Haldar, Chanchal
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- Hydrodealkenylative C(sp3)–C(sp2) bond fragmentation
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Chemical synthesis typically relies on reactions that generate complexity through elaboration of simple starting materials. Less common are deconstructive strategies toward complexity—particularly those involving carbon-carbon bond scission. Here, we introduce one such transformation: the hydrodealkenylative cleavage of C(sp3)–C(sp2) bonds, conducted below room temperature, using ozone, an iron salt, and a hydrogen atom donor. These reactions are performed in nonanhydrous solvents and open to the air; reach completion within 30 minutes; and deliver their products in high yields, even on decagram scales. We have used this broadly functionality tolerant transformation to produce desirable synthetic intermediates, many of which are optically active, from abundantly available terpenes and terpenoid-derived precursors. We have also applied it in the formal total syntheses of complex molecules.
- Smaligo, Andrew J.,Swain, Manisha,Quintana, Jason C.,Tan, Mikayla F.,Kim, Danielle A.,Kwon, Ohyun
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p. 681 - 685
(2019/06/11)
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- OXIDATIVE CLEAVAGE OF OLEFINS, EPOXIDES AND ALCOHOLS
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Provided is a process for producing a compound I comprising at least one functional group chosen in the group consisting of epoxy group, hydroxyl group and carbonyl group and by reacting a compound J comprising at least one functional group chosen in the group consisting of alkenyl group, epoxy group and hydroxyl group with an an oxidant in the presence of solid amphiphilic catalytic particles A and solid amphiphilic catalytic particles B.
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Page/Page column 23
(2019/02/06)
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- Regioselective 1,2-Diol Rearrangement by Controlling the Loading of BF3·Et2O and Its Application to the Synthesis of Related Nor-Sesquiterene- and Sesquiterene-Type Marine Natural Products
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The regiocontrolled rearrangement of 1,2-diols has been achieved by controlling the loading of BF3·Et2O. Its applicability is showcased by the divergent synthesis of austrodoral, austrodoric acid, and 8-epi-11-nordriman-9-one, as well as a formal synthesis of siphonodictyal B and liphagal. A new light is shed on piancol-type rearrangements that will be useful in diversity-oriented synthesis of related natural products.
- Wang, Jun-Li,Li, Hui-Jing,Wang, Hong-Shuang,Wu, Yan-Chao
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supporting information
p. 3811 - 3814
(2017/07/26)
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- Metal-free, catalytic regioselective oxidative conversion of vinylarenes: A mild approach to phenylacetic acid derivatives
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A new synthetic approach towards the synthesis of phenylacetic acids from aromatic alkenes has been developed for the first time under mild conditions by employing non-toxic reagents such as molecular iodine and oxone. This metal-free catalytic regioselective oxygenation of vinylarenes proceeds via tandem iodofunctionalization/de-iodination induced rearrangement.
- Kodumuri, Srujana,Peraka, Swamy,Mameda, Naresh,Chevella, Durgaiah,Banothu, Rammurthy,Nama, Narender
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p. 6719 - 6723
(2016/02/03)
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- Selective transition-metal-free vicinal cis-dihydroxylation of saturated hydrocarbons
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A transition-metal-free cis-dihydroxylation of saturated hydrocarbons under ambient reaction conditions has been developed. The described approach allows a direct and selective synthesis of vicinal diols. The new reaction thereby proceeds via radical iodination and a sequence of oxidation steps. A broad scope of one-pot dual C(sp3)-H bond functionalization for the selective synthesis of vicinal syn-diols was demonstrated.
- Bering, Luis,Antonchick, Andrey P.
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p. 452 - 457
(2016/12/30)
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- Supported Sulfonic Acids: Solid Catalysts for Batch and Continuous-Flow Synthetic Processes
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It's easy being green! In this work, supported sulfonic acids were used as effective catalysts for different classes of reactions. They have the advantage of being cheap, safe, and easy to recycle. Reaction conditions are mild, have good atom economy, and work-up steps are very easy, satisfying essential parameters of the "green chemistry" philosophy. Application of these catalysts to continuous-flow processes resulted in a considerable improvement in efficiency.
- Piscopo, Calogero G.
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p. 383 - 388
(2015/06/30)
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- Regioselective Cleavage of Electron-Rich Double Bonds in Dienes to Carbonyl Compounds with [Fe(OTf)2(mix-BPBP)] and a Combination of H2O2 and NaIO4
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A method for the regioselective transformation of dienes to carbonyl compounds has been developed. Electron-rich olefins react selectively to yield valuable aldehydes and ketones. The method is based on the catalyst [Fe(OTf)2(mix-BPBP)] with an oxidant combination of H2O2 (1.0 equiv.) and NaIO4 (1.5 equiv.); it uses mild conditions and short reaction times, and it outperforms other olefin cleavage methodologies. The combination of an Fe-based catalyst, [Fe(OTf)2(mix-BPBP)], and the oxidants H2O2 and NaIO4 can discriminate between electronically different double bonds and oxidatively cleave the electron-rich bond in dienes to yield aldehydes and ketones in a regioselective manner. The reaction requires mild conditions (0-50 C) and short reaction times (70 min).
- Spannring, Peter,Yazerski, Vital A.,Chen, Jianming,Otte, Matthias,Weckhuysen, Bert M.,Bruijnincx, Pieter C. A.,Klein Gebbink, Robertus J. M.
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p. 3462 - 3466
(2015/08/06)
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- A procedure for the preparation of Ti-Beta zeolites for catalytic epoxidation with hydrogen peroxide
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Ti-Beta zeolite has been successfully prepared via a reproducible and scalable two-step post-synthesis strategy, which consists of creating vacant T sites with associated silanol groups by dealumination of H-Beta and subsequent dry impregnation of the resulting Si-Beta with titanocene dichloride. The mechanism of Ti incorporation into the framework of Beta is investigated by diffuse reflectance infrared Fourier transform (DRIFT) and multinuclear solid-state nuclear magnetic resonance (SSNMR) spectroscopy. Characterization results obtained from diffuse reflectance ultraviolet-visible (UV-vis) and X-ray photoelectron spectroscopy (XPS) reveal that the majority of incorporated Ti species exist in the form of isolated tetrahedrally coordinated Ti(iv) in the zeolite framework while a minority exists in the form of isolated octahedrally coordinated Ti(vi) at framework or extra-framework positions. The obtained Ti-Beta zeolites are highly active and selective catalysts for the epoxidation of unsaturated ketones, e.g. 2-cyclohexen-1-one, with hydrogen peroxide as an oxidant. A quasilinear correlation between the epoxidation rate and the number of framework Ti(iv) species could be drawn evidencing that these Ti(iv) species are responsible for the epoxidation activity of the Ti-Beta zeolites under study. The impact of preparation parameters and reaction conditions on the catalytic performances of the Ti-Beta zeolites in the epoxidation of unsaturated organic compounds with hydrogen peroxide is discussed in detail. the Partner Organisations 2014.
- Tang, Bo,Dai, Weili,Sun, Xiaoming,Guan, Naijia,Li, Landong,Hunger, Michael
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p. 2281 - 2291
(2014/04/17)
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- Acidic three-liquid-phase microemulsion systems based on balanced catalytic surfactant for epoxidation and sulfide oxidation under mild conditions
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Didecyldimethylammonium tungstate has been designed as a balanced catalytic surfactant to form acidic three-liquid-phase microemulsion systems at room temperature in the presence of water, a non-chlorinated solvent and dimethyldioctylammonium salts (hydrogen sulfate and dihydrogen phosphate). The triphasic system is efficient for the oxidation of olefins, sulfides and thiophenes under mild conditions. Moreover, the recovery and reusability of the catalyst, the straightforward separation of products and catalysts in two distinct phases as well as the possible use of environmentally friendly solvents such as tert-butyl acetate, make this system particularly attractive for catalytic oxidation reactions involving hydrogen peroxide as the primary oxidant under acidic or neutral conditions.
- Fressancourt-Collinet, Marion,Hong, Bing,Leclercq, Loic,Alsters, Paul L.,Aubry, Jean-Marie,Nardello-Rataj, Veronique
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supporting information
p. 409 - 420
(2013/05/22)
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- Stereo- and regioselectivity in the P450-catalyzed oxidative tandem difunctionalization of 1-methylcyclohexene
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The selective partial oxidation of small non-functionalized molecules using biocatalysis based on P450 monooxygenases is known to be difficult due to the expected poor regio- and stereoselectivity, but in this study it was nevertheless attempted. 1-Methyl
- Roiban, Gheorghe-Doru,Agudo, Rubén,Reetz, Manfred T.
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p. 5306 - 5311
(2013/07/05)
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- Cyclic seleninate esters as catalysts for the oxidation of sulfides to sulfoxides, epoxidation of alkenes, and conversion of enamines to α-hydroxyketones
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Cyclic seleninate esters serve as catalysts for the rapid oxidation of sulfides to sulfoxides, alkenes to epoxides, and enamines to α-hydroxyketones. Optimal conditions were found that minimize the overoxidation of the product sulfoxides to sulfones and the hydrolysis of epoxides to diols. In some examples such as styrene derivatives, oxidative cleavage was observed instead of epoxidation. The enamine oxidations proceed via the initial formation of dimeric 2,5-diamino-1,4-dioxane species, which were hydrolyzed in situ to the final products. The structure of one such dimer was confirmed by X-ray crystallography.
- Mercier, Eric A.,Smith, Chris D.,Parvez, Masood,Back, Thomas G.
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scheme or table
p. 3508 - 3517
(2012/06/04)
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- Homogeneous dihydroxylation of olefins catalyzed by OsO4 2- immobilized on a dendritic backbone with a tertiary nitrogen at its core position
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OsO42- immobilized on a poly(benzyl ether) dendrimer with a tertiary nitrogen at its core position efficiently catalyzed the homogeneous dihydroxylation of olefins with a low level of osmium leaching. The dendritic osmium catalyst could be applied to the wide range of olefins. Furthermore, the dendritic osmium catalyst was recovered by reprecipitation and then reused up to five times.
- Fujita, Ken-Ichi,Inoue, Kensuke,Tsuchimoto, Teruhisa,Yasuda, Hiroyuki
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p. 1594 - 1598
(2013/02/23)
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- Hydrodeoxygenation of lignin model compounds over a copper chromite catalyst
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The hydrodeoxygenation of benzyl alcohol, phenol, anisole, o-cresol, catechol, guaiacol, and vanillyl alcohol were carried out from 150 to 275 °C at 50 bar H2 with a CuCr2O4·CuO catalyst in a decalin solvent. The hydroxymethyl group of benzyl alcohol was found to be highly reactive towards hydrogenolysis to form toluene. Demethoxylation of anisole to form benzene was found to be the primary reaction pathway in contrast to demethylation and transalkylation reactions, which are more prevalent for conventional hydrotreating catalysts. The hydroxyl group of phenol strongly activated the aromatic ring towards hydrogenation forming cyclohexanol which was subsequently dehydrated and hydrogenated to form cyclohexane. Reaction networks of increasing complexity were devised for the major functional groups and integrated to describe the most complex molecule studied, vanillyl alcohol.
- Deutsch, Keenan L.,Shanks, Brent H.
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p. 144 - 150
(2013/03/13)
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- Stereoselective selenium catalyzed dihydroxylation and hydroxymethoxylation of alkenes
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The selenium atom of the selenocysteine plays a crucial role in the reduction of peroxides. Herein we showed that, in the absence of a thiol cofactor, the same aminoacid efficiently catalyzed the dihydroxylation of carbon-carbon double bonds leading to the stereoselective formation of 1,2-diols at room temperature and in on water conditions. Alternatively, in the presence of methanol, the corresponding β-methoxyalcohol can be prepared. The stereoselectivity of the reaction will be discussed and NMR evidences of the actual catalyst are here reported.
- Santi, Claudio,Di Lorenzo, Rosalia,Tidei, Caterina,Bagnoli, Luana,Wirth, Thomas
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p. 10530 - 10535,6
(2012/12/12)
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- Bronsted acid-catalyzed dihydroxylation of olefins in aqueous medium
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The trans-dihydroxylation of olefins occurs efficiently by aqueous hydrogen peroxide catalyzed by p-toluenesulfonic acid at 50°C, allowing the catalyst reuse and an outstanding substrate functional group tolerance such as tert-butoxycarbonylamino (BocNH), benzyloxycarbonylamino (CbzNH), benzyloxy (OBn), tosyloxy (OTs), hindered ketal, (2-trimethylsilyl)ethoxymethoxy (OSEM), benzylamino (NBz), benzyloxy (OBz) and free amino acid. Copyright
- Rosatella, Andreia A.,Afonso, Carlos A.M.
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supporting information; experimental part
p. 2920 - 2926
(2012/01/03)
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- Manipulating the Expression Rate and Enantioselectivity of an Epoxide Hydrolase by Using Directed Evolution
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We describe here a strategy to improve the expression efficiency and enantioselectivity of Aspergillus niger epoxide hydrolase (ANEH) by directed evolution. Based on a blue-colony screening system using the LacZα (β-galactosidase α peptide) complementation solubility reporter, several ANEH variants out of 15000 transformants from a random-mutagenesis library were identified that show improved recombinant expression in E. coli. Among them, Pro221Ser was subsequently used as a template for iterative saturation mutagenesis (ISM) at sites around the ANEH binding pocket. Following four rounds of ISM, a highly enantioselective mutant was identified that catalyzes the hydrolytic kinetic resolution of racemic glycidyl phenyl ether with a selectivity factor of E=160 in favor of the (S)-diol compared to WT ANEH characterized by E=4.6. Expression of this mutant is 50 times higher than that of WT ANEH. It also serves as an excellent stereoselective catalyst in the hydrolytic kinetic resolution and desymmetrization of several other structurally diverse epoxides. Copyright
- Reetz, Manfred T.,Zheng, Huabao
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experimental part
p. 1529 - 1535
(2012/05/31)
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- An expedient procedure for the oxidative cleavage of olefinic bonds with PhI(OAc)2, NMO, and Catalytic OsO4
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(Figure Presented) PhI(OAc)2 In the presence of OsO4 (cat.) and 2,6-lutidine cleaves oleflnlc bonds to yield the corresponding carbonyl compounds, albeit, In some cases, with a-hydroxy ketones as byproduct. A more practical and clean protocol to effect oxidative cleavage of olefinic bonds involves NMO, OsO4 (cat.), 2,6-lutidine, and PhI(OAc) 2.
- Nicolaou,Adsool, Vikrant A.,Hale, Christopher R. H.
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supporting information; experimental part
p. 1552 - 1555
(2010/06/16)
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- Manipulating the stereoselectivity of limonene epoxide hydrolase by directed evolution based on iterative saturation mutagenesis
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Limonene epoxide hydrolase from Rhodococcus erythropolis DCL 14 (LEH) is known to be an exceptional epoxide hydrolase (EH) because it has an unusual secondary structure and catalyzes the hydrolysis of epoxides by a rare one-step mechanism in contrast to the usual two-step sequence. From a synthetic organic viewpoint it is unfortunate that LEH shows acceptable stereoselectivity essentially only in the hydrolysis of the natural substrate limonene epoxide, which means that this EH cannot be exploited as a catalyst in asymmetric transformations of other substrates. In the present study, directed evolution using iterative saturation mutagenesis (ISM) has been tested as a means to engineer LEH mutants showing broad substrate scope with high stereoselectivity. By grouping individual residues aligning the binding pocket correctly into randomization sites and performing saturation mutagenesis iteratively using a reduced amino acid alphabet, mutants were obtained which catalyze the desymmetrization of cyclopentene-oxide with stereoselective formation of either the (R,R)- or the (S,S)-diol on an optional basis. The mutants prove to be excellent catalysts for the desymmetrization of other meso-epoxides and for the hydrolytic kinetic resolution of racemic substrates, without performing new mutagenesis experiments. Since less than 5000 tranformants had to be screened for achieving these results, this study contributes to the generalization of ISM as a fast and reliable method for protein engineering. In order to explain some of the stereoselective consequences of the observed mutations, a simple model based on molecular dynamics simulations has been proposed.
- Zheng, Huabao,Reetz, Manfred T.
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supporting information; experimental part
p. 15744 - 15751
(2011/02/21)
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- Sharpless asymmetric dihydroxylation of olefins in water-surfactant media with recycling of the catalytic system by membrane nanofiltration
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This paper presents a new and more sustainable alternative approach for the Sharpless catalytic asymmetric dihydroxylation (AD) of olefins using a water/surfactant systemas reaction media. The AD reaction was performed using several cationic and anionic surfactants allowing yields and enantiomeric excesses higher or comparable with the conventional systems (using organic mixtures). The use of this water/surfactant medium offers the additional advantage of performing the reactions without the need of a slow addition of olefins. Asymmetric dihydroxylation of 1-hexene in a 1.5 mM sodium cholate aqueous solution, using N-methylmorpholine N-oxide (NMO) as co-oxidant was selected as model systemto evaluate the feasibility of recycling the Sharpless catalytic systemby nanofiltration. The reaction media was processed by nanofiltration, the product was isolated in the permeate, whereas the catalytic systemand surfactant were retained by the membrane and recycled through six successive reactions, improving the catalyst turn-over number. The experimental results were compared with the ones calculated on the basis of mass balances, membrane rejections to product and reaction yields.
- Branco, Luis C.,Ferreira, Frederico Castelo,Santos, Jose L.,Crespo, Joao G.,Afonso, Carlos A. M.
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supporting information; experimental part
p. 2086 - 2098
(2009/09/07)
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- Diastereo and enantioselective synthesis of 1,2-diols promoted by electrophilic selenium reagents
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Here we report the first example in which the phenylseleno group is directly substituted by a hydroxy function. The reaction is promoted by the PhSeOSO3H generated "in situ" by oxidation of (PhSe)2 with (NH4)2S2O8 at reflux in a 3:1 mixture of MeCN-H2O. I
- Santi,Tiecco,Testaferri,Tomassini,Santoro,Bizzoca
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experimental part
p. 956 - 960
(2009/04/06)
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- Catalytic asymmetric dihydroxylation of olefins using polysulfone-based novel microencapsulated osmium tetroxide
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A polysulfone based novel polymer-supported osmium catalyst has been developed. The catalyst was prepared from commercially available polysulfone, based on a microencapsulation technique and was employed in the asymmetric dihydroxylation of various olefins using (DHQD)2PHAL as the chiral ligand and NMO as the co-oxidant in H2O-acetone-CH3CN (1:1:1). The catalyst was recovered by simple filtration and was reused to obtain excellent yields with good enantioselectivity up to five times.
- Malla Reddy,Srinivasulu,Venkat Reddy,Narasimhulu,Venkateswarlu
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p. 5285 - 5288
(2007/10/03)
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- Method for the dihydroxylation of olefins using transition metal catalysts
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This invention relates to process for dihydroxylation of olefins using transition metal catalysts to obtain monofunctional, bifunctional, and/or polyfunctional 1,2-diols of the formula (I) R1R2C(OH)—C(OH)R3R4??(I) where R1to R4are defined herein, by reacting an olefin of the formula (II) R1R2C═CR3R4??(II) where R1to R4are defined as for formula (I), with molecular oxygen in the presence of an osmium, ruthenium, or manganese compound in water or a water-containing solvent mixture at a pH of from 7.5 to 13.
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Page column 8
(2008/06/13)
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- NOVEL PROCESS FOR PRODUCING 1,2-DIOL
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A process for producing a 1,2-diol through the reaction of an olefin with hydrogen peroxide. The process is highly efficient and highly selective and catalyst recovery and reuse are easy. It does not use any strong acid or strong base causative of apparatus corrosion. The process for producing a 1,2-diol is characterized by reacting an olefin with hydrogen peroxide in the presence of a polymer having a sulfo group.
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- Efficient photocatalytic oxidation of cycloalkenes by dihydroxo(tetraphenylporphyrinato)-antimony supported on silica gel under visible light irradiation
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In order to develop a photocatalyst operating under visible light irradiation, silica gel-supported dihydroxo(tetraphenylporphyrinato)antimony (V) complex, [SbTPP(OH)2]+/SiO2, was prepared. The photocatalytic oxidation of cycloalkenes with oxygen molecule was performed on [SbTPP(OH)2]+/SiO2 particles under irradiation of fluorescent light. The photocatalytic oxidation of cycloalkenes gave the corresponding cis-1,2-epoxycycloalkane, 2-cycloalkene-1-ol, and trans-1,2-cycloalkanediol.
- Shiragami, Tsutomu,Makise, Ryu-Ichi,Inokuchi, Yousuke,Matsumoto, Jin,Inoue, Haruo,Yasuda, Masahide
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p. 736 - 737
(2007/10/03)
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- Studies on the asymmetric dihydroxylation of advanced bryostatin C-ring segments
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The asymmetric dihydroxylation reaction of early stage and advanced Bryostatin C-ring precursors was evaluated. For homoallylic ethers and alcohols, several AD ligands were investigated including a novel class of quinidine-alkynes.
- Seidel, Martin C.,Smits, René,Stark, Christian B. W.,Frackenpohl, Jens,Gaertzen, Oliver,Hoffmann, H. Martin R.
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p. 1391 - 1398
(2007/10/03)
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- Activation of hydrogen peroxide through hydrogen-bonding interaction with acidic alcohols: Epoxidation of alkenes in phenol
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(Matrix presented) Electrophilic activation of hydrogen peroxide can be achieved in acidic alcohol solvents without the need for a metal catalyst. This concept is illustrated by the epoxidation of alkenes with H2O 2 employing phenol as a solvent. It is proposed that intermolecular hydrogen bonding between H2O2 and phenol activates H 2O2 for oxygen-atom transfer. In this interaction, the role of phenol is purely catalytic.
- Wahlen, Joos,De Vos, Dirk E.,Jacobs, Pierre A.
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p. 1777 - 1780
(2007/10/03)
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- Zn(II)-catalyzed thiolysis of oxiranes in water under neutral conditions
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Thiolysis of a variety of 1,2-epoxides in water at 30 °C and pH 7.0 is strongly accelerated by ZnCl2 (10 mol %) except when amino- and carboxythiophenol are used. The aqueous medium and the catalyst were recovered and reused in various runs wit
- Fringuelli, Francesco,Pizzo, Ferdinando,Tortoioli, Simone,Vaccaro, Luigi
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p. 8248 - 8251
(2007/10/03)
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- Direct formation of pinacols from olefins over various titano-silicates
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The epoxidation and successive pinacol formation of tri- and tetraalkyl-substituted olefins using Ti-β/H2O2/H2O as the catalytic system has been investigated. Aluminum-free Ti-β exhibits better activity and pinacol selectivity than TS-1, TS-2, Ti-MCM-22, and mesoporous Ti-MCM-41. Pinacol (vic-diol) is obtained as the major product with small amounts of the side products pinacolone, alcohol (via hydration), and oligomers. The conversion and pinacol selectivity increase with an increase in reaction temperature and time. The change in product distribution with reaction time over Ti-β shows that the epoxide is the initial product which undergoes a secondary reaction to give pinacol as the major product. The conversion and H2O2 selectivity decrease with the bulkiness of the substituents at the C=C bond but the selectivity of pinacol is not significantly affected. The reactivity of cyclic 1-methyl-1-cyclohexene is considerably lower than that of the corresponding open-chain analogue 2-methyl-2-butene. The symmetrical tetramethyl-substituted 2,3-dimethyl-2-butene led to the formation of small amount of dimers over medium-pore titanium silicates TS-1, TS-2, and Ti-MCM-22. The epoxidation of these substituted olefins proceeded more rapidly when using acetonitrile as a cosolvent than under triphase conditions. Mechanistically, the primary epoxide product undergoes acid-catalyzed nucleophilic ring opening by H2O molecules to give pinacol.
- Sasidharan,Wu, Peng,Tatsumi, Takashi
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p. 260 - 265
(2007/10/03)
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- Method for the asymmetric dihydroxylation of olefins, using osmium catalysts
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This invention relates to process for asymmetric dihydroxylation of olefins using osmium catalysts to obtain monofunctional, bifunctional, and/or polyfunctional chiral 1,2-diols of the formula (I) R1R2C(OH)—C(OH)R3R4??(I) where R1to R4are defined herein, by reacting an olefin of the formula (II) R1R2C═CR3R4??(II) where R1to R4are defined as for formula (I), with molecular oxygen in the presence of an osmium compound and a chiral amine ligand in water or a water-containing solvent mixture at a pH of from 8.5 to 13.
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- A new non-metal heterogeneous catalyst for the activation of hydrogen peroxide: A perfluorinated ketone attached to silica for oxidation of aromatic amines and alkenes
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A silane functionalized by octafluoroacetophenone was polymerized by the sol-gel method to form an insoluble silicate with perfluoroketone pendants; the silicate was used as a heterogeneous catalyst for the activation of aqueous hydrogen peroxide and the oxidation of aromatic amines and alkenes.
- Neimann,Neumann
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p. 487 - 488
(2007/10/03)
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- Directive effect of the 2- and 3-axial hydroxy groups that appeared in the complex metal hydride reduction of cyclohexanones
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A directive effect of the 2-axial hydroxy group appeared in the LiAlH4, NaBH4, and Zn(BH4)2 reduction of cyclohexanone, while the 3-axial hydroxy group exhibited a steric hindrance. The distance between the carbonyl carbon and the hydroxy group interacting with the hydride reagent was responsible for such a difference. In the reduction of Na[B(OAc)3H], the 2- and 3-axial hydroxycyclohexanones gave the products obtained by the hydride approaching from the side of the hydroxy group. The key point of the stereoselectivity was the formation of Na[B(OAc)2(OR)H, which was more reactive than the parent hydride, by exchanging the acetate ion with the alkoxide. Although the reduction was performed under the condition that the hydride/substrate ratio was 1, the conversion of the hydroxy ketone to an alcohol were 4, NaBH4, and Zn(BH4)2 reductions in tetrahydrofuran. The conversions in the NaBH4 reduction in ethanol were > 90%.
- Senda,Kikuchi,Inui,Itoh
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p. 237 - 242
(2007/10/03)
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- NaY zeolite as host for the selective heterogeneous oxidation of silanes and olefins with hydrogen peroxide catalyzed by methyltrioxorhenium
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The methyltrioxorhenium(MTO)-catalyzed oxidation of silanes to silanols and the epoxidation of various olefins by aqueous 85% H2O2 proceed in high yields and excellent product selectivities (no disiloxanes, diols) in the presence of the zeolite NaY. The oxidative species is located inside the 12- A supercages. This prevents the bimolecular condensation of the silanol to disiloxane by steric means and the Lewis-acid assisted hydrolysis of the epoxide to the diol.
- Adam, Waldemar,Saha-Moeller, Chantu R.,Weichold, Oliver
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p. 2897 - 2899
(2007/10/03)
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- Osmium-Catalyzed Dihydroxylation of Olefins Using Dioxygen or Air as the Terminal Oxidant
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The osmium-catalyzed dihydroxylation of various olefins using molecular oxygen or air as the stoichiometric oxidant is reported. Aromatic olefins yield the corresponding diols in good to excellent chemoselectivities under optimized pH conditions (pH = 10.4-12.0). Air can be used under moderate pressures (3-9 bar) instead of dioxygen as the reoxidant. By increasing the oxygen content of the solution, it is possible to achieve highly efficient conversion at low catalyst amount (catalyst/substrate = 1:4000). Tri- and tetrasubstituted olefins are oxidized at pH > 11 to give the corresponding 1,2-diols in good to very good yields without requiring the addition of sulfonamides or other hydrolysis agents. Studies of the dihydroxylation of functionalized olefins demonstrate that the reaction conditions tolerate a variety of functional groups. In the presence of dihydroquinine or dihydroquinidine derivatives (Sharpless ligands), asymmetric dihydroxylations occur with lower enantioselectivities than tose of the classical K3[Fe(CN)6] reoxidation system.
- Doebler, Christian,Mehltretter, Gerald M.,Sundermeier, Uta,Beller, Matthias
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p. 10289 - 10289
(2007/10/03)
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- Acid-catalyzed enzymatic hydrolysis of 1-methylcyclohexene oxide
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Limonene-1,2-epoxide hydrolase from Rhodococcus erythropolis DCL14, an enzyme involved in the limonene metabolism of this microorganism, catalyzes the enantioselective hydrolysis of 1-methylcyclohexene oxide. (1R,2S)-1- Methylcyclohexene oxide was the preferred substrate and it was mainly hydrolyzed to (1S,2S)-1-methylcyclohexane-1,2-diol, while (1S,2R)-1- methylcyclohexene oxide was converted more slowly and mainly yielded (1R,2R)- 1-methylcyclohexane-1,2-diol. The reaction proceeded with a high regioselectivity (C1:C2, 85:15). H218O-labelling experiments confirmed that the nucleophile was mainly incorporated at the most substituted carbon atom, suggesting that limonene-1,2-epoxide hydrolase uses an acid-catalyzed enzyme mechanism.
- Van Der Werf, Mariet J.,De Bont, Jan A. M.,Swarts, Henk J.
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p. 4225 - 4230
(2007/10/03)
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- Catalytic dihydroxylation of methylcyclohexene isomers in the presence of bromine-containing molybdenum compounds
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An investigation has been made of the kinetic relationships governing the dihydroxylation of methylcyclohexene isomers in the presence of Mo(V) and Mo(VI) oxobromides. It was established that the dihydroxylation of cyclo-olefins proceeds both via an intermediate stage of formation of the corresponding epoxy compound and directly from the cyclo-olefin by breakdown of the peroxy complex. Kinetic equations have been derived, and a kinetic model of the process has been constructed which describes the main routes of the reaction.
- Alimardanov,Akhundova,Veliyeva,Aliyev
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p. 445 - 454
(2007/10/03)
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