- Ferrous Ion Catalysis of Reactions of Nucleophiles with Aryl Halides
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Reactions of ketone enolate ions and of diethyl phosphite ion with bromo- and iodobenzene in ammonia or dimethyl sulfoxide solution occur in preparatively useful amounts under catalysis by iron(II) salts, apparently via the SRN1 mechanism.
- Galli, Carlo,Bunnett, J. F.
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- A NEW PALLADIUM CATALYZED AROMATIC ACETONYLATION BY ACETONYLTRIBUTYLTIN
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The reaction of acetonyltributyltin, prepared from tributyltin methoxide and isopropenyl acetate in situ, with aryl bromide in the presence of a catalytic amount of PdCl2(o-tolyl3P)2 was found to give arylacetones in good yields.
- Kosugi, Masanori,Suzuki, Mikio,Hagiwara, Isao,Goto, Katsuhisa,Saitoh, Kyoko,et al.
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- Developing backbone-modified Mor-DalPhos ligand variants for use in palladium-catalyzed C-N and C-C cross-coupling
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The present contribution describes the systematic structural diversification of the ?°2-P,N DalPhos ligand family in an effort to improve catalytic efficiency in the monoarylation of ammonia and acetone. The study is focused primarily on modifying the backbone phenylene linker, while retaining the same bite angle and steric bulk as the Mor-DalPhos ligand through the use of P(1-Ad)2 and morpholine donors. Eight new variants of Mor-DalPhos were prepared; two of these feature a pyridine linker (L1, L2), and five others feature either electron-donating (L3, L4) or electron-withdrawing (L5-L7) substituents on the phenylene linker. Additionally, thiomorpholino substitution (L8) was performed to investigate the effects of a possible tridentate coordination mode. Precatalyst complexes of the general formula LPd(cinnamyl)Cl were prepared and characterized in both solution and solid state. Solution studies demonstrated a significant degree of lability in the Pd-N bond, whereby dynamic behavior is seen to be dependent on the nature of the ligand backbone. The utility of these new ligands in the palladium-catalyzed monoarylation of ammonia or acetone was then surveyed. Notably, pyridine-derived ligand variants (L1, L2) were observed to out-perform parent Mor-DalPhos in the latter transformations.
- MacLean, Mark A.,Wheaton, Craig A.,Stradiotto, Mark
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- A novel chromium trioxide catalyzed oxidation of primary alcohols to the carboxylic acids
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A novel CrO3 catalyzed oxidation of primary alcohols to the carboxylic acids is reported. The oxidation proceeds smoothly with only 1-2 mol % of CrO3 and 2.5 equivalents of H3IO6 in wet MeCN to give the carboxylic acids in excellent yield. No significant racemization is observed for alcohols with adjacent chiral centers. Secondary alcohols are cleanly oxidized to ketones.
- Zhao, Mangzhu,Li, Jing,Song, Zhiguo,Desmond, Richard,Tschaen, David M.,Grabowski, Edward J. J.,Reider, Paul J.
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- Hydration and alkoxylation of alkynes catalyzed by NHC-Au-OTf
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The NHC-Au-OTf [NHC = 1,3-bis(2,6-di-isopropylphenyl)-imidazol-2-ylidene] catalyst was tested in the alkoxylation and hydration of alkynes in a wide set of neoteric solvents for the first time. We found that most of these solvents (ethyl lactate, glycerol, propylene carbonate, d-limonene, γ-valerolactone, and p-cymene) are comparable or better solvents with respect to traditional VOSs. An important beneficial effect of γ-valerolactone was found in the hydration of inactive diphenylacetylene and one order of magnitude higher TOF was obtained with respect to the literature values. Kinetic experiments and DFT calculations seem to indicate that the polarity of the solvent and the presence of suitable proton acceptor/donor functionalities on the solvent itself could be taken into account.
- Gatto, Mattia,Baratta, Walter,Belanzoni, Paola,Belpassi, Leonardo,Del Zotto, Alessandro,Tarantelli, Francesco,Zuccaccia, Daniele
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- N,O-ligated Pd(ii) complexes for catalytic alcohol oxidation
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N,O-ligated Pd(ii) complexes show considerable promise for the oxidation of challenging secondary aliphatic alcohols. The crystal structures of the highly active complexes containing the 8-hydroxyquinoline-2-carboxylic acid (HCA) and 8-hydroxyquinoline-2-sulfonic acid (HSA) ligands have been obtained. The (HSA)Pd(OAc)2 system can effectively oxidise a range of secondary alcohols, including unactivated alcohols, within 4-6 h using loadings of 0.5 mol%, while lower loadings (0.2 mol%) can be employed with extended reaction times. The influence of reaction conditions on catalyst degradation was also examined in these studies.
- Dornan, Laura M.,Clendenning, Grainne M. A.,Pitak, Mateusz B.,Coles, Simon J.,Muldoon, Mark J.
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- One-pot oxidation of aromatic and cyclic hydrocarbons using the Au (III) and Pd (II) catalyst under microwave irradiation
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We report here in highly efficient one-pot catalytic system which utilizes in situ generated sodium ferrate for the oxidation of aromatic and cyclic hydrocarbons in the presence of Au (III) and Pd (II) metal ions catalyst under ecofriendly green synthetic method. Results of these studies revealed that Au (III) catalytic system gave higher yield as compared with Pd (II) catalytic system because of the higher electrode potential of Au(III) than Pd(II). All compounds were characterized by infrared and NMR spectral analysis. Copyright
- Srivastava, Manish,Srivastava, Anamika,Goyal, Ashu,Mishra, Aakanksha,Tomer, Preeti,Dwivedi, Jaya,Kishore
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- Bismuth(III) oxide perchlorate promoted rearrangement of epoxides to aldehydes and ketones
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Aryl-substituted epoxides and aliphatic epoxides with a tertiary epoxide carbon undergo smooth rearrangement in the presence of 10-50 mol% bismuth(III) oxide perchlorate, BiOClO4·XH2O, to give carbonyl compounds. The rearrangement is regioselective with aryl substituted epoxides and a single carbonyl compound arising from cleavage of benzylic C-O bond is formed. BiOClO4·XH2O is relatively non-toxic, insensitive to air and inexpensive, making this catalyst an attractive alternative to more corrosive and toxic Lewis acids such as BF3·Et2O or INCl3 currently used to effect epoxide rearrangements. (C) 2000 Elsevier Science Ltd.
- Anderson, Andrew M.,Blazek, Jesse M.,Garg, Parie,Payne, Brian J.,Mohan, Ram S.
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- A recyclable catalytic system based on a temperature-responsive catalyst
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(Figure Presented) A new concept for catalytic reactions in aqueous media is demonstrated by using a temperature-responsive polymer support, poly(N-alkylacrylamide), which is converted into a catalyst by assembly with phosphotungstic acid. At high temperature, the catalyst is highly active in the oxidation of alcohols with H2O2 owing to the formation of emulsions, whereas the product and catalyst are easily separated at low temperature (see scheme).
- Hamamoto, Hiromi,Suzuki, Yachiyo,Yamada, Yoichi M. A.,Tabata, Hidetsugu,Takahashi, Hideyo,Ikegami, Shiro
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- Alcohol oxidation via recyclable hydrophobic ionic liquid-supported IBX
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The first ionic hydrophobic liquid-supported 1-hydroxy-1,2-benziodoxole-3(1H)-one-1-oxide (IBX) reagent was prepared for oxidizing alcohols. In this study, a hydrophobic ionic liquid-supported IBX reagent was synthesized and described. This hydrophobic ionic liquid-supported IBX reagent was able to be recovered and used in a recyclable reaction system by re-oxidation and washing.
- Koguchi, Shinichi,Mihoya, Aya,Mimura, Minato
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- Practical synthesis of (E)-pent-3-en-2-one and its conversion to (E)-2-triethylsilyloxypenta-1,3-diene
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An improved procedure for the preparation of (E)-pent-3-en-2-one in high yields utilizing a Friedel-Crafts type alkylation of crotonyl chloride with trimethylaluminum is reported. Conversion of this enone into the corresponding enol silyl ether is also described.
- Arisawa,Torisawa,Nakagawa
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- Silica-supported HgSO4/H2SO4: A convenient reagent for the hydration of alkynes under mild conditions
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The silica-supported aqueous-phase catalyst (SAPC) approach has proven convenient for efficiently performing the hydration of alkynes with HgSO 4/H2SO4 to give the corresponding carbonyl compounds in dichloromethane under mild conditions. The use of this solid reagent significantly improves the reaction work-up as it merely involves filtering and evaporating the solvent.
- Mello, Rossella,Alcalde-Aragonés, Ana,González-Nú?ez, María Elena
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- KBrO3/ZrClO2 · 8H2O: An efficient reagent system for the oxidation of alcohols
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KBrO3 in the presence of ZrOCl2 · 8H 2O can be used as an effective oxidizing agent for the conversion of alcohols to their corresponding carbonyl compounds. All reactions were performed under mild and completely heterogeneous conditions in good to high yields. Copyright Taylor & Francis, Inc.
- Shirini, Farhad,Zolfigol, Mohammad Ali,Mollarazi, Esmail
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- Novel synthesis of methyl ketones based on the blaise reaction
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A facile two-step synthesis of methyl ketones from alkyl nitriles via the Blaise conversion of nitriles into -keto esters and acid-mediated hydrolysis followed by decarboxylation of the resulting -keto esters is described. Copyright Taylor & Francis Group, LLC.
- Rao, H. Surya Prakash,Padmavathy,Vasantham,Rafi, Shaik
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- Solvent-free oxidation of alcohols by t-butyl hydroperoxide catalyzed by water-soluble copper complex
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The catalytic system composed of CuCl2 and 2,2'-biquinoline-4,4'-dicarboxylic acid dipotassium salt (BQC), was found to be highly efficient for the selective oxidation of secondary benzylic, allylic and propargylic alcohols to the corresponding ketones, with aqueous t-butyl hydroperoxide under phase-transfer catalysis conditions. The catalytic system is stable and can be recycled and reused several times without loss of activity.
- Ferguson, Gabriel,Ajjou, Abdelaziz Nait
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- Recyclable soluble polyisobutylene-bound oxidizing agents
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This Letter describes the use of alkene-terminated polyisobutylene (PIB) as a support for oxidizing agents. Two oxidizing agents, an ionically immobilized PIB-bound perruthenate oxidation catalyst and a PIB-bound 2-iodoxybenzoic acid (IBX) oxidizing reagent, were studied. A perruthenate catalyst ionically bound to PIB was prepared by binding the perruthenate anion to PIB that contained either a terminal tetraalkylammonium or an imidazolium salt. The PIB supported ammonium and imidazolium perruthenate were both selectively soluble in heptane and effective in the oxidation of alcohols. While these PIB-bound perruthenate catalysts could be readily separated from products, recycling was less successful. A PIB bound 2-iodoxybenzoic (IBX) oxidizing agent was coupled to a PIB support with an ester bond. It was highly soluble in nonpolar and moderately polar organic solvents. By taking advantage of PIB's heptane solubility, the spent IBX reagent could be easily separated from products by a liquid/liquid heptane/acetonitrile biphasic separation. The recovered IBX reagent could then be regenerated and used in multiple cycles for oxidation of both primary and secondary alcohols.
- Samunual, Peerada,Bergbreiter, David E.
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- On the Mechanism of the Baeyer-Villiger Oxidation of Ketones by Bis(trimethylsilyl) Peroxomonosulfate. Intermediacy of Dioxiranes
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The Baeyer-Villiger oxidation of cyclohexanone (2a) and of acetophenone (2b) by bis(trimethylsilyl)peroxomonosulfate (1) has been reinvestigated using (18)O-labeling techniques.Starting with doubly labeled Me3Si(18)O(18)OSO3SiMe3, mass spectrometric analyses allowed determination of the amount of label appearing in the carbonyl and the OR moiety of the ester (or of the lactone).It has been observed that 2a also promotes the decomposition of 1 to yield oxygen gas, which was analyzed for its (18)O content.Furthermore, ketones 2a, 4-heptanone, and acetone were foundto enhance significantly the rate of oxidation of 1-methylcyclohexene (10) and of trans-β-methylstyrene (13) by 1, yielding 2-methylcyclohexanone (12) and 1-phenylpropanone (15) derived from the isomerization of the initially formed epoxides.These observations, most notably the (18)O-tracer results, point to a mechanism involving the intermediacy of dioxiranes as the prevailing pathway.
- Camporeale, Michele,Fiorani, Tiziana,Troisi, Luigino,Adam, Waldemar,Curci, Ruggero,Edwards, John O.
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- Cadmium Chloride-Magnesium-Water: a New System for Regioselective Transformation of Conjugated Nitroalkenes to Ketocompounds; Conversion of 6-Nitro-Δ5-steroids to 6-Ketosteroids
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Reaction of 6-nitro-Δ5-steroids and nitroalkenes in tetrahydrofuran with CdCl2-Mg-H2O furnished 6-ketosteroids and ketocompounds, respectively, in good yield.
- Bordoloi, Manobjyoti
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- Catalytic Wacker-type Oxidations Using Visible Light Photoredox Catalysis
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A combined palladium/photoredox catalytic system for the efficient oxidation of terminal olefins to the corresponding methyl ketones is presented. The interplay of air, water, and light leads to a protocol in which the stoichiometric oxidants required for oxidative palladium catalysis are substituted with catalytic, single-electron transfer processes. Detailed mechanistic investigations revealed the role of the key components, in situ generated species, and catalysts. A broad range of substrates was examined in homogeneous as well as heterogeneous photoredox protocols, delivering the desired products in good yields.
- Ho, Yee Ann,Paffenholz, Eva,Kim, Hyun Jin,Orgis, Benjamin,Rueping, Magnus,Fabry, David C.
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- Efficient aerial oxidation of different types of alcohols using ZnO nanoparticle–MnCO3-graphene oxide composites
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Graphene–metal nanocomposites have been found to remarkably enhance the catalytic performance of metal nanoparticle-based catalysts. In continuation of our previous report, in which highly reduced graphene oxide (HRG)-based nanocomposites were synthesized and evaluated, we present nanocomposites of graphene oxide (GRO) and ZnO nanoparticle-doped MnCO3 ([ZnO–MnCO3/(1%)GRO]) synthesized via a facile, straightforward co-precipitation technique. Interestingly, it was noticed that the incorporation of GRO in the catalytic system could noticeably improve the catalytic efficiency compared to a catalyst (ZnO–MnCO3) without GRO, for aerial oxidation of benzyl alcohol (BzOH) employing O2 as a nature-friendly oxidant under base-free conditions. The impacts of various reaction factors were thoroughly explored to optimize reaction conditions using oxidation of BzOH to benzaldehyde (BzH) as a model substrate. The catalysts were characterized using X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, Energy dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET), and Raman spectroscopy. The (1%)ZnO–MnCO3/(1%)GRO exhibited significant specific activity (67 mmol.g?1.hr?1) with full convversion of BzOH and >99% BzH selectivity within just 6 min. The catalytic efficiency of the (1%)ZnO–MnCO3/(1%)GRO nanocomposite was significantly better than the (1%)ZnO–MnCO3/(1%)HRG and (1%)ZnO–MnCO3 catalysts, presumably due to the existence of oxygen-possessing groups on the GRO surface and as well as a very high surface area that could have been instrumental in uniformly dispersing the active sites of the catalyst, i.e., ZnO–MnCO3. Under optimum circumstances, various kinds of alcohols were selectively transformed to respective carbonyls with full convertibility over the (1%)ZnO–MnCO3/(1%)GRO catalyst. Furthermore, the highly effective (1%)ZnO–MnCO3/(1%)GRO catalyst could be successfully reused and recycled over five consecutive runs with a marginal reduction in its performance and selectivity.
- Adil, Syed Farooq,Assal, Mohamed E.,Shaik, Mohammed Rafi,Kuniyil, Mufsir,Hashmi, Azhar,Khan, Mujeeb,Khan, Aslam,Tahir, Muhammad Nawaz,Al-Warthan, Abdulrahman,Siddiqui, Mohammed Rafiq H.
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- DECARBOXYLATION OXYDANTE DES ACIDES CARBOXYLIQUES ALIPHATIQUES PAR UN SYSTEME CUIVRE(I)OXYGENE
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A new oxidative decarboxylation reaction converts carboxylic acids 1 or 2 (Z =OH) to the corresponding carbonyl compounds 3, in the presence of oxygen and catalytic amounts of copper(I), probably via transient coppe(III) carboxylates.
- Toussaint, Olivier,Capdevielle, Patrice,Maumy, Michel
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- The flavoprotein-catalyzed reduction of aliphatic nitro-compounds represents a biocatalytic equivalent to the Nef-reaction
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The bioreduction of aliphatic sec-nitro compounds catalyzed by purified flavoproteins from the old-yellow-enzyme family unexpectedly furnished the corresponding carbonyl compounds instead of the expected amines and thus represents a biocatalytic equivalent to the Nef-reaction. The pathway was shown to proceed via initial reduction of the nitro-group to yield the nitroso-derivative, which spontaneously tautomerized to yield the more stable oxime, which was enzymatically reduced in a second step to furnish a hydrolytically unstable imine-species, which spontaneously hydrolyzed to finally give a carbonyl compound and ammonia.
- Durchschein, Katharina,Ferreira-Da Silva, Bianca,Wallner, Silvia,MacHeroux, Peter,Kroutil, Wolfgang,Glueck, Silvia Maria,Faber, Kurt
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- EFFET DU BENZENE DANS LA REACTION DE GRIGNARD SUR LES NITRILES
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Use of benzene containing one equivalent of ether as solvent in Grignard reactions of nitriles at room temperature, leads to increased yields of the corresponding ketones compared to results obtained for the same reactions in ether.A useful consequence of this is that undesirable side reactions are virtually eliminated.
- Canonne, Persephone,Foscolos, George B.,Lemay, Gilles
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- HALOKETONE DEHALOGENATION BY IODIDE ION
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NaI in aqueous acid-THF is an efficient reagent for the dehalogenation of α-haloketones.
- Gemal, A.L.,Luche, J.L.
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- Efficient synthesis of enantiopure amines from alcohols using resting: E. coli cells and ammonia
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α-Chiral amines are pivotal building blocks for chemical manufacturing. Stereoselective amination of alcohols is receiving increased interest due to its higher atom-efficiency and overall improved environmental footprint compared with other chemocatalytic and biocatalytic methods. We previously developed a hydrogen-borrowing amination by combining an alcohol dehydrogenase (ADH) with an amine dehydrogenase (AmDH) in vitro. Herein, we implemented the ADH-AmDH bioamination in resting Escherichia coli cells for the first time. Different genetic constructs were created and tested in order to obtain balanced expression levels of the dehydrogenase enzymes in E. coli. Using the optimized constructs, the influence of several parameters towards the productivity of the system were investigated such as the intracellular NAD+/NADH redox balance, the cell loading, the survival rate of recombinant E. coli cells, the possible toxicity of the components of the reaction at different concentrations and the influence of different substrates and cosolvents. In particular, the cofactor redox-balance for the bioamination was maintained by the addition of moderate and precise amounts of glucose. Higher concentrations of certain amine products resulted in toxicity and cell death, which could be alleviated by the addition of a co-solvent. Notably, amine formation was consistent using several independently grown E. coli batches. The optimized E. coli/ADH-AmDH strains produced enantiopure amines from the alcohols with up to 80% conversion and a molar productivity up to 15 mM. Practical applicability was demonstrated in a gram-scale biotransformation. In summary, the present E. coli-ADH-AmDH system represents an important advancement towards the development of 'green', efficient and selective biocatalytic processes for the amination of alcohols.
- Houwman, Joseline A.,Knaus, Tanja,Costa, Magda,Mutti, Francesco G.
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- Emulation of racemase activity by employing a pair of stereocomplementary biocatalysts
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Racemization is the key step to turn a kinetic resolution process into dynamic resolution. A general strategy for racemization under mild reaction conditions by employing stereoselective biocatalysts is presented, in which racemization is achieved by employing a pair of stereocomplementary biocatalysts that reversibly interconvert an sp3 to a sp2 center. The formal interconversion of the enantiomers proceeds via a prochiral sp 2 intermediate the formation of which is catalyzed either by two stereocomplementary enzymes or by a single enzyme with low stereoselectivity. By choosing appropriate reaction conditions, the amount of the prochiral intermediate is kept to a minimum. This general strategy, which is applicable to redox enzymes (e.g., by acting on R2CHOH and R2CHNHR groups) and lyase-catalyzed addition-elimination reactions, was proven for the racemization of secondary alcohols by employing alcohol dehydrogenases. Thus, enantiopure chiral alcohols were used as model substrates and were racemized either with highly stereoselective biocatalysts or by using (rarely found) non-selective enzymes.
- Gruber, Christian C.,Nestl, Bettina M.,Gross, Johannes,Hildebrandt, Petra,Bornscheuer, Uwe T.,Faber, Kurt,Kroutil, Wolfgang
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- Metalloporphyrin as an efficient catalyst in the regioselective isomerization of epoxides to carbonyl compounds
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Regioselective ring-opening isomerization of epoxides to carbonyl compounds can effectively be catalyzed by iron (III) tetraphenylporphyrin, Fe(tpp)ClO4.
- Takanami, Toshikatsu,Hirabe, Rina,Ueno, Masayoshi,Hino, Fumio,Suda, Kohji
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- Direct conversion of allyl arenes to aryl ethylketones via a TBHP-mediated palladium-catalyzed tandem isomerization-Wacker oxidation of terminal alkenes
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A TBHP-mediated palladium-catalyzed tandem isomerization-Wacker oxidation of terminal alkenes was developed. This methodology provides a new efficient and simple route for conversion of a range of allyl arenes directly into aryl ethylketones in good yields with high chemoselectivity.
- Zhao, Jinwu,Liu, Li,Xiang, Shijian,Liu, Qiang,Chen, Huoji
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- Selective Wacker-type oxidation of terminal alkenes and dienes using the Pd(II)/molybdovanadophosphate (NPMoV)/O2 system
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Selective Wacker-type oxidation of long-chain terminal alkenes to methylketones was successfully achieved by using Pd(OAc)2/molybdovanadophosphate (NPMoV)/O2 system. The selectivity of the reaction increased by slow addition of the alkenes to the catalytic solution. The oxidation of α,ω-dienes was also examined, and the selectivity of the oxidation was found to depend on the chain length of the dienes used.
- Yokota, Takahiro,Sakakura, Aki,Tani, Masayuki,Sakaguchi, Satoshi,Ishii, Yasutaka
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- Aromatic Acetonylation Promoted by Manganese(III) and Cerium(IV) Salts
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Treatment of aromatic hydrocarbons with acetone and manganese(III) acetate gave rise to arylacetones in yields ranging from 25 percent with chlorobenzene to 74 percent with anisole.Cerium(IV) salts were also successfully used as promoters but gave lower yields.The reactions were relatively free of side products except with toluene.Isomer distributions, relative rates, and partial rate factors were determined for acetonylation of anisole, toluene, chlorobenzene, and fluorobenzene.A Hammett plot of the log of the partial rate factors for the manganese(III) system vs. ?-constants gave a slope, ρ, of -2.4 +/- 0.3.An isotope effect kH/kD = 3.8 was observed for the manganese(III)-promoted reaction with acetone-d6, indicating rate-determining proton loss from acetone.The overall mechanism involves formation and attack of acetonyl radicals onto the aromatic hydrocarbon followed by subsequent oxidative deprotonation of the resulting ?-radical complex.The acetonyl radical exhibits appreciable electron-deficient character in its substitution behavior with aromatic hydrocarbons.
- Kurz, Michael E.,Baru, Vijayalakshmi,Nguyen, P-Nhi
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- THE DIMESITYLBORON GROUP IN ORGANIC CHEMISTRY. 6 HYDROBORATIONS WITH DIMESITYLBORANE.
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Dimesitylborane, 1, is a readily available, solid, stable borane that is the most selective known reagent for the regioselective hydroboration of unsymmetrical alkynes.In addition all-alkynes are selectively hydroborated compared with even terminal alkenes.The hydroboration of alkenes with 1 is slow and sensitive to steric factors, thus giving promise of good selectivity between different types of alkene.
- Pelter, Andrew,Singaram, Saraswathi,Brown, Herbert
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- Platinum(II) diphosphinamine complexes for the efficient hydration of alkynes in micellar media
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Highly active monomeric bis-cationic platinum(II) catalysts bearing small bite angle diphosphinamine [N,N-bis(diarylphosphino)amine] 'PNP' ligands efficiently catalyze Markovnikov hydration of terminal and internal alkynes to the corresponding ketones in water. Catalyst solubilization in water is achieved via ion pairing with anionic micelles formed by surfactant addition. The micelles ensure dissolution of apolar alkynes and promote the intimate contact between reagents and catalyst, while in organic-water media in the absence of surfactants the reaction is sluggish. Hydration products can be isolated by means of extraction with an apolar solvent and the catalyst, that remains confined in the aqueous phase, can be recycled up to four times without loss of catalytic activity. Copyright
- Trentin, Francesco,Chapman, Andrew M.,Scarso, Alessandro,Sgarbossa, Paolo,Michelin, Rino A.,Strukul, Giorgio,Wass, Duncan F.
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- Direct Asymmetric Reductive Amination for the Synthesis of Chiral β-Arylamines
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The highly efficient and direct asymmetric reductive amination of arylacetones catalyzed by an iridium complex for the preparation of enantiomerically pure β-arylamines is described. The monodentate phosphoramidite ligand exhibits superb reactivity (TONs of up to 20 000) and enantioselectivity (up to 99 % ee). Additives played important roles in this reductive coupling reaction. Asymmetric reductive coupling of a ketone and an amine is a straightforward and atom-economic approach for preparing optically enriched amines. The highly efficient and direct asymmetric reductive amination of arylacetones, catalyzed by an iridium complex, supplies enantiomerically pure β-arylamines. The new phosphoramidite ligands reported show superb reactivity and enantioselectivity in this reductive coupling. M.S.=molecular sieves, TFA=trifluoroacetic acid.
- Huang, Haizhou,Liu, Xiaoyan,Zhou, Le,Chang, Mingxin,Zhang, Xumu
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- SMALL MOLECULE INHIBITORS OF ACETYL COENZYME A SYNTHETASE SHORT CHAIN 2 (ACSS2)
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The present invention relates to compounds of formula (I). The compounds may be used to modulate the acetyl coenzyme A synthetase short chain 2 (ACSS2) protein and may thereby treat, ameliorate or prevent a disease selected from cancer, bacterial infection, viral infection, parasitic infection, fungal infection, neurodegenerative disease, neurological disorder, cerebrovascular disease, cardiovascular disease, non- alcoholic fatty liver disease and obesity. Alternatively, or additionally, the compounds maybe used to promote healthy ageing.
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- Highly ordered mesoporous hybrid silica functionalized with ionic liquid framework supported copper and its application in the oxidation of alcohols
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A highly ordered organic-inorganic hybrid nanomaterial containing copper N-heterocyclic carbene complex (Cu-NHC@Pyrm-OMS) was synthesized and characterized using various techniques including FTIR, MAS NMR, XRD, TGA, SEM, and TEM. Cu-NHC@Pyrm-OMS nanomaterial is highly efficient heterogeneous system towards the selective oxidation of primary and secondary alcohols to corresponding aldehydes and ketones under mild conditions. Moreover, the supported copper nanocatalyst exhibited outstanding stability and could be reused at least ten times, remaining almost unchanged from initial activity. This work has focused on sustainable and green chemistry that use recoverable nanocatalyst, clean oxidant and aqueous media.
- Rajabi, Fatemeh,Bahrami, Nazli,Vessally, Esmail,Luque, Rafael
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- An efficient heterogeneous Cu(I) complex for the catalytic oxidation of alcohols and sulfides: synthesis, characterization, and investigation of the catalyst activity
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A heterogeneous Cu(I) complex was synthesized by reaction of C5H4NC(O)NHP(O)[NHC(CH3)3]2 (L) with CuCl and used as a catalyst for green oxidation of aromatic alcohols and sulfides. According to the characterization results obtained from 31P NMR, UV-Vis, FT-IR, mass, XRD, elemental analysis, and molar conductivity techniques, the chemical formula of the complex (1) was suggested as [CuClL2]. Parameters on the catalytic activity (reaction temperature, the substrate to oxidant molar ratio, catalyst amount, and solvent type) were optimized, using H2O2 as a green oxidant, and excellent conversion amounts (100%) were achieved under optimal conditions. Moreover, the generality and recyclability of the catalyst were tested and confirmed. A comparison between the oxidation results of the alcohol and sulfide in the presence of 1 with other catalysts indicated that in most cases 1 showed better efficiency, in a more reasonable reaction time and conditions.
- Oroujzadeh, Nasrin,Baradaran, Zahra,Sedrpoushan, Alireza
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p. 2344 - 2364
(2021/08/06)
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- Manganese Catalyzed Enantioselective Epoxidation of α,β-Unsaturated Amides with H2O2
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Herewith, we report the enantioselective epoxidation of electron-deficient cis- and trans-α,β-unsaturated amides with the environmentally benign oxidant H2O2. The catalysts - manganese complexes with bis-amino-bis-pyridine and structurally related ligands - exhibit reasonably high efficiency (up to 100 TON) and excellent chemo- and enantioselectivity (up to 100% and 99% ee, respectively). Crucially, the cis-enamides epoxidation enantioselectivity and yield are dramatically enhanced by the presence of NH-moiety, which effect can be explained by the hydrogen bonding interaction between the cis-enamide substrate and the manganese based oxygen transferring species. (Figure presented.).
- Ottenbacher, Roman V.,Kurganskiy, Vladimir I.,Talsi, Evgenii P.,Bryliakov, Konstantin P.
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supporting information
p. 2778 - 2782
(2021/04/29)
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- 2-Iodosylbenzoic acid activated by trifluoromethanesulfonic anhydride: Efficient oxidant and electrophilic reagent for preparation of iodonium salts
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2-Iodosylbenzoic acid in the presence of trifluoromethanesulfonic anhydride is an efficient oxidant and electrophilic reagent useful for preparation of the corresponding alkenyl and aryliodonium salts. Compared to the previously reported methods of electr
- Huss, Christopher D.,Kitamura, Tsugio,Saito, Akio,Yoshimura, Akira,Zhdankin, Viktor V.
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supporting information
p. 16434 - 16437
(2021/10/01)
-
- Meta Selective C-H Borylation of Sterically Biased and Unbiased Substrates Directed by Electrostatic Interaction
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An electrostatically directed meta borylation of sterically biased and unbiased substrates is described. The borylation follows an electrostatic interaction between the partially positive and negative charges between the ligand and substrate. With this strategy, it has been demonstrated that a wide number of challenging substrates, especially 4-substituted substrates, can selectively be borylated at the meta position. Moreover, unsubstituted substrates also displayed excellent meta selectivity. The reaction employs a bench-stable ligand and proceeds at a milder temperature, precluding the need to synthesize a bulky and sophisticated ligand/template.
- Chaturvedi, Jagriti,Haldar, Chabush,Bisht, Ranjana,Pandey, Gajanan,Chattopadhyay, Buddhadeb
-
supporting information
p. 7604 - 7611
(2021/05/26)
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- Gold-Catalyzed [3+2]-Annulations of α-Aryl Diazoketones with the Tetrasubstituted Alkenes of Cyclopentadienes: High Stereoselectivity and Enantioselectivity
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This work reports gold-catalyzed [3+2]-annulations of α-diazo ketones with highly substituted cyclopentadienes, affording bicyclic 2,3-dihydrofurans with high regio- and stereoselectivity. The reactions highlights the first success of tetrasubstituted alkenes to undergo [3+2]-annulations with α-diazo carbonyls. The enantioselective annulations are also achieved with high enantioselectivity using chiral forms of gold and phosphoric acid. Our mechanistic analysis supports that cyclopentadienes serve as nucleophiles to attack gold carbenes at the more substituted alkenes, yielding gold enolates that complex with chiral phosphoric acid to enhance the enantioselectivity.
- Chen, Ching-Nung,Cheng, Wei-Min,Wang, Jian-Kai,Chao, Tzu-Hsuan,Cheng, Mu-Jeng,Liu, Rai-Shung
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supporting information
p. 4479 - 4484
(2021/01/21)
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- Sulfonium ion-promoted traceless Schmidt reaction of alkyl azides
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Schmidt reaction by sulfonium ions is described. General primary, secondary, and tertiary alkyl azides were converted to the corresponding carbonyl or imine compounds without any trace of the activators. This bond scission reaction through 1,2-migration of C-H and C-C bonds was accessible to the one-pot substitution reaction.
- Ardiansah, Bayu,Kakiuchi, Kiyomi,Morimoto, Tsumoru,Tanimoto, Hiroki,Tomohiro, Takenori
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p. 8738 - 8741
(2021/09/08)
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- Asymmetric Catalytic Epoxidation of Terminal Enones for the Synthesis of Triazole Antifungal Agents
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An enantioselective epoxidation of α-substituted vinyl ketones was realized to construct the key epoxide intermediates for the synthesis of various triazole antifungal agents. The reaction proceeded efficiently in high yields with good enantioselectivities by employing a chiral N,N′-dioxide/ScIII complex as the chiral catalyst and 35% aq. H2O2 as the oxidant. It enabled the facile transformation for optically active isavuconazole, efinaconazole, and other potential antifungal agents.
- Feng, Xiaoming,He, Qianwen,Liu, Xiaohua,Zhang, Dong,Zhang, Fengcai
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supporting information
p. 6961 - 6966
(2021/09/11)
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- Method for preparing ketone compound from olefin
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The invention belongs to the technical field of organic chemical synthesis, and discloses a method for preparing a ketone compound from olefin by using an iron catalyst. According to the invention, the ligand and the iron salt form an iron catalyst in the on-site reaction, the raw materials in the formula are easy to obtain, and the synthesis is simple. By using the catalyst, olefin can be efficiently converted into ketone compounds, and compared with a palladium catalyst, the price is very low, and the catalyst is suitable for industrial application.
- -
-
Paragraph 0041-0043
(2021/08/19)
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- Aerobic epoxidation of styrene over Zr-based metal-organic framework encapsulated transition metal substituted phosphomolybdic acid
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Catalytic epoxidation of styrene with molecular oxygen is regarded as an eco-friendly alternative to producing industrially important chemical of styrene oxide (STO). Recent efforts have been focused on developing highly active and stable heterogeneous catalysts with high STO selectivity for the aerobic epoxidation of styrene. Herein, a series of transition metal monosubstituted heteropolyacid compounds (TM-HPAs), such as Fe, Co, Ni or Cu-monosubstituted HPA, were encapsulated in UiO-66 frameworks (denoted as TM-HPA@UiO-66) by direct solvothermal method, and their catalytic properties were investigated for the aerobic epoxidation of styrene with aldehydes as co-reductants. Among them, Co-HPA@UiO-66 showed relatively high catalytic activity, stability and epoxidation selectivity at very mild conditions (313 K, ambient pressure), that can achieve 82 % selectivity to STO under a styrene conversion of 96 % with air as oxidant and pivalaldehyde (PIA) as co-reductant. In addition, the hybrid composite catalyst can also efficiently catalyze the aerobic epoxidation of a variety of styrene derivatives. The monosubstituted Co atoms in Co-HPA@UiO-66 are the main active sites for the aerobic epoxidation of styrene with O2/PIA, which can efficiently converting styrene to the corresponding epoxide through the activation of the in-situ generated acylperoxy radical intermediate.
- Hu, Dianwen,Song, Xiaojing,Zhang, Hao,Chang, Xinyu,Zhao, Chen,Jia, Mingjun
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-
- Competition Between Cα-S and Cα-Cβ Bond Cleavage in β-Hydroxysulfoxides Cation Radicals Generated by Photoinduced Electron Transfer?
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A kinetic and product study of the 3-cyano-N-methyl-quinolinium photoinduced monoelectronic oxidation of a series of β-hydroxysulfoxides has been carried out to investigate the competition between Cα-S and Cα-Cβ bond cleavage within the corresponding cation radicals. Laser flash photolysis experiments unequivocally established the formation of sulfoxide cation radicals showing their absorption band (λmax ≈ 520?nm) and that of 3-CN-NMQ? (λmax ≈ 390?nm). Steady-state photolysis experiments suggest that, in contrast to what previously observed for alkyl phenyl sulfoxide cation radicals that exclusively undergo Cα-S bond cleavage, the presence of a β-hydroxy group makes, in some cases, the Cα-Cβ scission competitive. The factors governing this competition seem to depend on the relative stability of the fragments formed from the two bond scissions. Substitution of the β-OH group with -OMe did not dramatically change the reactivity pattern of the cation radicals thus suggesting that the observed favorable effect of the hydroxy group on the Cα-Cβ bond cleavage mainly resides on its capability to stabilize the carbocation formed upon this scission.
- Lapi, Andrea,D'Alfonso, Claudio,Del Giacco, Tiziana,Lanzalunga, Osvaldo
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p. 1310 - 1321
(2021/06/07)
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- Markovnikov Wacker-Tsuji Oxidation of Allyl(hetero)arenes and Application in a One-Pot Photo-Metal-Biocatalytic Approach to Enantioenriched Amines and Alcohols
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The Wacker-Tsuji aerobic oxidation of various allyl(hetero)arenes under photocatalytic conditions to form the corresponding methyl ketones is presented. By using a palladium complex [PdCl2(MeCN)2] and the photosensitizer [Acr-Mes]ClO4 in aqueous medium and at room temperature, and by simple irradiation with blue led light, the desired carbonyl compounds were synthesized with high conversions (>80%) and excellent selectivities (>90%). The key process was the transient formation of Pd nanoparticles that can activate oxygen, thus recycling the Pd(II) species necessary in the Wacker oxidative reaction. While light irradiation was strictly mandatory, the addition of the photocatalyst improved the reaction selectivity, due to the formation of the starting allyl(hetero)arene from some of the obtained by-products, thus entering back in the Wacker-Tsuji catalytic cycle. Once optimized, the oxidation reaction was combined in a one-pot two-step sequential protocol with an enzymatic transformation. Depending on the biocatalyst employed, i. e. an amine transaminase or an alcohol dehydrogenase, the corresponding (R)- and (S)-1-arylpropan-2-amines or 1-arylpropan-2-ols, respectively, could be synthesized in most cases with high yields (>70%) and in enantiopure form. Finally, an application of this photo-metal-biocatalytic strategy has been demonstrated in order to get access in a straightforward manner to selegiline, an anti-Parkinson drug. (Figure presented.).
- Albarrán-Velo, Jesús,Gotor-Fernández, Vicente,Lavandera, Iván
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supporting information
p. 4096 - 4108
(2021/08/19)
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- Iridium-catalyzed highly chemoselective and efficient reduction of nitroalkenes to nitroalkanes in water
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An iridium-catalyzed highly chemoselective and efficient transfer hydrogenation reduction of structurally diverse nitroalkenes was realized at very low catalyst loading (S/C = up to 10000 or 20?000), using formic acid or sodium formate as a traceless hydride donor in water. Excellent functionality tolerance is also observed. The turnover number and turnover frequency of the catalyst reach as high as 18?600 and 19?200 h-1, respectively. An inert atmosphere protection is not required. The reactivities of nitroalkenes are dependent on their substitution pattern, and the pH value is a key factor to accomplish the complete conversion and excellent chemoselectivity. Purification of products is achieved by simple extraction without column chromatography. The reduction procedure is facilely amplified to 10 g scale at 10?000 S/C ratio. The potential of this green reduction in enantioselective hydrogenation has been demonstrated.
- Chen, Yang,Liu, Changmeng,Xu, Dong,Xu, Jiaxi,Yang, Zhanhui
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p. 6050 - 6058
(2021/08/23)
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- Aryl C-F bond functionalization preparation method
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The invention relates to the technical field of organic compound synthesis, in particular to an aryl C-F bond functionalization preparation method. A fluorobenzene compound and a nucleophilic reagent react under the action of a composite catalyst, wherein the composite catalyst is formed by mixing a visible light catalyst and a metal catalyst. The photocatalyst is adopted, the reaction process is safe and controllable, and operation in the preparation and production process is simplified; a purple LED is used as a reaction energy source and is green and environment-friendly, the energy utilization rate is high, and conversion from light energy to chemical energy can be efficiently realized; in the reaction, a simple nucleophilic reagent is used for attacking free radical cation species generated under a visible light catalysis condition, so that a target product with an extremely wide range is efficiently and greenly prepared; the operation steps are simplified, and the reaction route is shortened; and moreover, the forward reaction rate is high, and the production efficiency is remarkably improved.
- -
-
Paragraph 0052; 0089-0093
(2021/09/29)
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- Cu-Catalyzed Synthesis of Benzoxazole with Phenol and Cyclic Oxime
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A Cu-catalyzed straightforward synthesis of benzoxazoles from free phenols and cyclic oxime esters is reported. The mild reaction conditions tolerate various electron-withdrawing and electron-donating functional groups on both substrates, affording benzoxazoles in moderate to good yields. With this protocol, large-scale syntheses of Ezutromid and Flunoxaprofe in one or two steps are demonstrated. A catalytic mechanism, which includes Cu-catalyzed amination via inner-sphere electron transfer and consequent annulation, is proposed.
- Wang, Dong-Hui,Wang, Zheng-Hai
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supporting information
(2022/01/20)
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- A General Regioselective Synthesis of Alcohols by Cobalt-Catalyzed Hydrogenation of Epoxides
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A straightforward methodology for the synthesis of anti-Markovnikov-type alcohols is presented. By using a specific cobalt triphos complex in the presence of Zn(OTf)2 as an additive, the hydrogenation of epoxides proceeds with high yields and selectivities. The described protocol shows a broad substrate scope, including multi-substituted internal and terminal epoxides, as well as a good functional-group tolerance. Various natural-product derivatives, including steroids, terpenoids, and sesquiterpenoids, gave access to the corresponding alcohols in moderate-to-excellent yields.
- Beller, Matthias,Junge, Kathrin,Leischner, Thomas,Li, Wu,Liu, Weiping
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supporting information
p. 11321 - 11324
(2020/05/16)
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- Erbium-Catalyzed Regioselective Isomerization-Cobalt-Catalyzed Transfer Hydrogenation Sequence for the Synthesis of Anti-Markovnikov Alcohols from Epoxides under Mild Conditions
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Herein, we report an efficient isomerization-transfer hydrogenation reaction sequence based on a cobalt pincer catalyst (1 mol %), which allows the synthesis of a series of anti-Markovnikov alcohols from terminal and internal epoxides under mild reaction conditions (≤55 °C, 8 h) at low catalyst loading. The reaction proceeds by Lewis acid (3 mol % Er(OTf)3)-catalyzed epoxide isomerization and subsequent cobalt-catalyzed transfer hydrogenation using ammonia borane as the hydrogen source. The general applicability of this methodology is highlighted by the synthesis of 43 alcohols from epoxides. A variety of terminal (23 examples) and 1,2-disubstituted internal epoxides (14 examples) bearing different functional groups are converted to the desired anti-Markovnikov alcohols in excellent selectivity and yields of up to 98%. For selected examples, it is shown that the reaction can be performed on a preparative scale up to 50 mmol. Notably, the isomerization step proceeds via the most stable carbocation. Thus, the regiochemistry is controlled by stereoelectronic effects. As a result, in some cases, rearrangement of the carbon framework is observed when tri-and tetra-substituted epoxides (6 examples) are converted. A variety of functional groups are tolerated under the reaction conditions even though aldehydes and ketones are also reduced to the respective alcohols under the reaction conditions. Mechanistic studies and control experiments were used to investigate the role of the Lewis acid in the reaction. Besides acting as the catalyst for the epoxide isomerization, the Lewis acid was found to facilitate the dehydrogenation of the hydrogen donor, which enhances the rate of the transfer hydrogenation step. These experiments additionally indicate the direct transfer of hydrogen from the amine borane in the reduction step.
- Liu, Xin,Longwitz, Lars,Spiegelberg, Brian,T?njes, Jan,Beweries, Torsten,Werner, Thomas
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p. 13659 - 13667
(2020/11/30)
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- METHOD FOR PRODUCING BENZOYL FORMIC ACID COMPOUND AND PYRIDAZINE COMPOUND
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The present invention provides an industrially-advantageous process for preparing a benzoyl formic acid compound, and an efficient process for preparing a pyridazine compound using the same process. Specifically, the present invention provides a process for preparing a compound represented by formula (2), which comprises a step (B): a step of reacting a compound represented by formula (1) with a nitrosyl sulfuric acid in water to produce the compound represented by formula (2).
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-
Paragraph 0105
(2020/12/18)
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- Homobenzylic Oxygenation Enabled by Dual Organic Photoredox and Cobalt Catalysis
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Activation of aliphatic C(sp3)-H bonds in the presence of more activated benzylic C(sp3)-H bonds is often a nontrivial, if not impossible task. Herein we show that leveraging the reactivity of benzylic C(sp3)-H bonds to achieve reactivity at the homobenzylic position can be accomplished using dual organic photoredox/cobalt catalysis. Through a two-part catalytic system, alkyl arenes undergo dehydrogenation followed by an anti-Markovnikov Wacker-type oxidation to grant benzyl ketone products. This formal homobenzylic oxidation is accomplished with high atom economy without the use of directing groups, achieving valuable reactivity that traditionally would require multiple chemical transformations.
- McManus, Joshua B.,Griffin, Jeremy D.,White, Alexander R.,Nicewicz, David A.
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supporting information
p. 10325 - 10330
(2020/07/27)
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- Blue Light-Promoted N?H Insertion of Carbazoles, Pyrazoles and 1,2,3-Triazoles into Aryldiazoacetates
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Blue light irradiation of aryldiazoacetates leads to the formation of free carbenes, which can react with carbazoles, pyrazoles and 1,2,3-triazoles to afford the corresponding N?H inserted products. These reactions are performed under air and at room temperature, allowing the mild preparation of a variety of motifs found in biologically relevant targets. (Figure presented.).
- Stivanin, Mateus L.,Fernandes, Alessandra A. G.,da Silva, Amanda F.,Okada, Celso Y.,Jurberg, Igor D.
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p. 1106 - 1111
(2020/01/25)
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- MnO2as a terminal oxidant in Wacker oxidation of homoallyl alcohols and terminal olefins
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Efficient and mild reaction conditions for Wacker-type oxidation of terminal olefins of less explored homoallyl alcohols to β-hydroxy-methyl ketones have been developed by using a Pd(ii) catalyst and MnO2 as a co-oxidant. The method involves mild reaction conditions and shows good functional group compatibility along with high regio- and chemoselectivity. While our earlier system of PdCl2/CrO3/HCl produced α,β-unsaturated ketones from homoallyl alcohols, the present method provided orthogonally the β-hydroxy-methyl ketones. No overoxidation or elimination of benzylic and/or β-hydroxy groups was observed. The method could be extended to the oxidation of simple terminal olefins as well, to methyl ketones, displaying its versatility. An application to the regioselective synthesis of gingerol is demonstrated.
- Fernandes, Rodney A.,Ramakrishna, Gujjula V.,Bethi, Venkati
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p. 6115 - 6125
(2020/10/27)
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- Tungstate ion (WO42-) confined in hydrophilic/hydrophobic nanomaterials functionalized br?nsted acidic ionic liquid as highly active catalyst in the selective aerobic oxidation of alcohols in water
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A Br?nsted acidic Ionic Liquid containing tungstate anion functionalized polysiloxane network (PMO-IL-WO42-) was synthesized by simple self-condensation of tungstic acid and zwitterionic organosilane precursor possessing both imidazolium and sulfonate groups. Characterization by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), thermal gravimetric analysis TGA, nitrogen porosimetry, solid-state NMR spectroscopy and elemental analysis confirmed that both imidazolium cation and tungstate anion of zwitterion are successfully incorporated inside the organosilica framework. The catalytic activity of resulting hybrid PMO-IL- WO42- material was studied in the selective aerobic oxidation of primary and secondary alcohols using an atmospheric pressure of air in pure water. Due to the ionic liquid-based charged surface containing hydrophilic sulfonic acid and tungstate group, the synergistic hydrophilic/hydrophobic and redox effect of PMO-IL-WO42- as water-friendly catalyst facilitates and enhances the activity and selectivity toward the target oxidative products in water and proved to have a particularly broad substrate scope for reliable aerobic oxidation reaction. Furthermore, the catalyst showed outstanding stability and could be easily separated and reused at least ten reactions run under the same conditions as fresh catalyst without any loss of catalytic activity and product selectivity.
- Luque, Rafael,Nafe, Mostafa,Rajabi, Fatemeh,Rezanejad Bardajee, Ghasem
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- INHIBITING CYCLIC AMP-RESPONSIVE ELEMENT-BINDING PROTEIN (CREB)
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The present disclosure is directed to inhibitors of the CBP/p300 family of bromodomains. The compounds can be useful in the treatment of disease or disorders associated with the inhibition of the CBP/p300 family of bromodomains. For instance, the disclosure is concerned with compounds and compositions for inhibition of the CBP/p300 family of bromodomains, methods of treating diseases or disorders associated with the inhibition of CBP/p300 family of bromodomains (e.g., certain forms of cancer), and methods of synthesis of these compounds.
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-
Paragraph 073
(2020/10/09)
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- Selective Cross-Dehydrogenative C(sp3)-H Arylation with Arenes
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Selective C(sp3)-C(sp2) bond construction is of central interest in chemical synthesis. Despite the success of classic cross-coupling reactions, the cross-dehydrogenative coupling between inert C(sp3)-H and C(sp2)-H bonds represents an attractive alternative toward new C(sp3)-C(sp2) bonds. Herein, we establish a selective inter-and intramolecular C(sp3)-H arylation of alcohols with nondirected arenes that thereby provides a general pathway to access a wide range of β-arylated alcohols, including tetrahydronaphthalen-2-ols and benzopyran-3-ols, with high to excellent chemo-and regioselectivity.
- Hao, Hong-Yan,Mao, Yang-Jie,Xu, Zhen-Yuan,Lou, Shao-Jie,Xu, Dan-Qian
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supporting information
p. 2396 - 2402
(2020/03/13)
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- Deracemization and Stereoinversion of Alcohols Using Two Mutants of Secondary Alcohol Dehydrogenase from Thermoanaerobacter pseudoethanolicus
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We developed a one-pot sequential two-step deracemization approach to chiral alcohols using two mutants of Thermoanaerobacter pseudoethanolicus secondary alcohol dehydrogenase (TeSADH). This approach relies on consecutive non-stereospecific oxidation of alcohols and stereoselective reduction of their prochiral ketones using two mutants of TeSADH with poor and good stereoselectivities, respectively. More specifically, W110G TeSADH enables a non-stereospecific oxidation of alcohol racemates to their corresponding prochiral ketones, followed by W110V TeSADH-catalyzed stereoselective reduction of the resultant ketone intermediates to enantiopure (S)-configured alcohols in up to > 99 percent enantiomeric excess. A heat treatment after the oxidation step was required to avoid the interference of the marginally stereoselective W110G TeSADH in the reduction step; this heat treatment was eliminated by using sol-gel encapsulated W110G TeSADH in the oxidation step. Moreover, this bi-enzymatic approach was implemented in the stereoinversion of (R)-configured alcohols, and (S)-configured alcohols with up to > 99 percent enantiomeric excess were obtained by this Mitsunobu-like stereoinversion reaction.
- Hamdan, Samir M.,Musa, Musa M.,Nafiu, Sodiq A.,Takahashi, Etsuko,Takahashi, Masateru
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- Catalytic Selective Oxidation of Primary and Secondary Alcohols Using Nonheme [Iron(III)(Pyridine-Containing Ligand)] Complexes
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The selective oxidation of different primary and secondary alcohols to carbonyl compounds by hydrogen peroxide was found to be catalyzed in conversion ranging from good to excellent by an iron(III) complex of a pyridine-containing macrocyclic ligand (Pc-L), without the need of any additive. The choice of the counteranion (Cl, Br, OTf) appeared to be of fundamental importance and the best results in terms of selectivity (up to 99 %) and conversion (up to 98 %) were obtained using the well-characterized [Fe(III)(Br)2(Pc-L)]Br complex, 4c. Magnetic moments in solid-state, also confirmed in solution ([D6]DMSO) by Evans NMR method, were calculated and point out to an iron metal center in the high spin state of 5/2. The crystal structure shows that the iron(III) center is coordinated by the four nitrogen atoms of the macrocycle and two bromide anions to form a distorted octahedral coordination environment. The catalytic oxidation of benzyl alcohol in acetonitrile was found occurring with better conversions and selectivities than in other solvents. The reaction proved to be quite general, tolerating aromatic and aliphatic alcohols, although very low yields were obtained for terminal aliphatic alcohols. Preliminary mechanistic studies are in agreement with a catalytic cycle promoted by a high-spin iron complex.
- Caselli, Alessandro,Gallo, Emma,Panza, Nicola,Rizzato, Silvia,Tseberlidis, Giorgio,di Biase, Armando
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supporting information
p. 6635 - 6644
(2020/10/30)
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- A Simple Biosystem for the High-Yielding Cascade Conversion of Racemic Alcohols to Enantiopure Amines
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The amination of racemic alcohols to produce enantiopure amines is an important green chemistry reaction for pharmaceutical manufacturing, requiring simple and efficient solutions. Herein, we report the development of a cascade biotransformation to aminate racemic alcohols. This cascade utilizes an ambidextrous alcohol dehydrogenase (ADH) to oxidize a racemic alcohol, an enantioselective transaminase (TA) to convert the ketone intermediate to chiral amine, and isopropylamine to recycle PMP and NAD+ cofactors via the reversed cascade reactions. The concept was proven by using an ambidextrous CpSADH-W286A engineered from (S)-enantioselective CpSADH as the first example of evolving ambidextrous ADHs, an enantioselective BmTA, and isopropylamine. A biosystem containing isopropylamine and E. coli (CpSADH-W286A/BmTA) expressing the two enzymes was developed for the amination of racemic alcohols to produce eight useful and high-value (S)-amines in 72–99 % yield and 98–99 % ee, providing with a simple and practical solution to this type of reaction.
- Li, Zhi,Tian, Kaiyuan
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supporting information
p. 21745 - 21751
(2020/09/21)
-
- Electronic Asymmetry of an Annelated Pyridyl-Mesoionic Carbene Scaffold: Application in Pd(II)-Catalyzed Wacker-Type Oxidation of Olefins
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The two donor modules of an annelated pyridyl-mesoionic carbene ligand (aPmic) have different σ- and π-bonding characteristics leading to its electronic asymmetry. A Pd(II) complex 1 featuring aPmic catalyzes the oxidation of a wide range of terminal olefins to the corresponding methyl ketones in good to excellent yields in acetonitrile. The catalytic reaction is proposed to proceed via syn-peroxypalladation and a subsequent rate-limiting 1,2-hydride shift, which is supported by kinetic studies. The electronic asymmetry of aPmic renders a well-defined coordination sphere at Pd. The favored arrangement of reactants on the metal center features an olefin trans to the pyridyl module and a tbutylperoxide trans to the carbene. This arrangement gains added stability by the π-delocalization paved by the compatible orbitals on Pd, the pyridyl module, and the olefin that is perpendicular to the Pd(aPmic) plane. The π-interactions are absent in an alternate arrangement wherein the olefin is trans to the carbene. Density functional theory studies reveal the matching orbital overlaps responsible for the preferred arrangement over the other. This work provides an orbital description for the electronic asymmetry of aPmic.
- Bera, Jitendra K.,Dutta, Indranil,Kunnikuruvan, Sooraj,Reshi, Noor U Din,Saha, Sayantani,Yadav, Suman
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p. 11385 - 11393
(2020/11/23)
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- Mild Deprotection of Dithioacetals by TMSCl/NaI Association in CH3CN
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A mild process using a combination of TMSCl and NaI in acetonitrile is used to regenerate carbonyl compounds from a variety of dithiane and dithiolane derivatives. This easy to handle and inexpensive protocol is also efficient to deprotect oxygenated and mixed acetals as 1,3-dioxanes, 1,3-dioxolanes and 1,3-oxathianes quantitatively. As a possible extension of this method, it was also shown that nitrogenated substrates such as hydrazones, N-tosylhydrazones, and ketimines reacted well under these conditions to give the expected ketones in high yields. The methodology proposed herein is a good alternative to the existing methods since it does not use metals, oxidants, reducing agents, acidic or basic media, and keto-products were obtained in high to excellent yields.
- Yao, Yunxin,Zhao, Guangkuan,Hamze, Abdallah,Alami, Mouad,Provot, Olivier
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p. 5775 - 5779
(2020/08/17)
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- Monoaurated: Vs. diaurated intermediates: Causality or independence?
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Diaurated intermediates of gold-catalysed reactions have been a long-standing subject of debate. Although diaurated complexes were regarded as a drain of active monoaurated intermediates in catalytic cycles, they were also identified as the products of gold-gold cooperation in dual-activation reactions. This study shows investigation of intermediates in water addition to alkynes catalysed by [(IPr)Au(CH3CN)(BF4)]. Electrospray ionisation mass spectrometry (ESI-MS) allowed us to detect both monoaurated and diaurated complexes in this reaction. Infrared photodissociation spectra of the trapped complexes show that the structure of the intermediates corresponds to α-gold ketone intermediates protonated or aurated at the oxygen atom. Delayed reactant labelling experiments provided the half life of the intermediates in reaction of 1-phenylpropyne (～7 min) and the kinetic isotope effects for hydrogen introduction to the carbon atom (KIE ～ 4-6) and for the protodeauration (KIE ～ 2). The results suggest that the ESI-MS detected monoaurated and diaurated complexes report on species with a very similar or the same kinetics in solution. Kinetic analysis of the overall reaction showed that the reaction rate is first-order dependent on the concentration of the gold catalyst. Finally, all results are consistent with the reaction mechanism proceeding via monoaurated neutral α-gold ketone intermediates only.
- Anania, Mariarosa,Ja?íková, Lucie,Zelenka, Jan,Shcherbachenko, Elena,Ja?ík, Juraj,Roithová, Jana
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p. 980 - 988
(2020/02/11)
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- Bromomethyl Silicate: A Robust Methylene Transfer Reagent for Radical-Polar Crossover Cyclopropanation of Alkenes
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A general protocol for visible-light-induced cyclopropanation of alkenes was developed with bromomethyl silicate as a methylene transfer reagent, offering a robust tool for accessing highly valuable cyclopropanes. In addition to α-aryl or methyl-substituted Michael acceptors and styrene derivatives, the unactivated 1,1-dialkyl ethylenes were also shown to be viable substrates. Apart from realizing the cyclopropanation of terminal alkenes, the methyl transfer reaction has been further demonstrated to be amenable to the internal olefins. The photocatalytic cyclopropanation of 1,3-bis(1-arylethenyl)benzenes was also achieved, giving polycyclopropane derivatives in excellent yields. With late-stage cyclopropanation as the key strategy, the synthetic utility of this transformation was also demonstrated by the total synthesis of LG100268.
- Luo, Wenping,Fang, Yewen,Zhang, Li,Xu, Tianhang,Liu, Yongjun,Li, Yan,Jin, Xiaoping,Bao, Jiakan,Wu, Xiaodong,Zhang, Zongyong
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supporting information
p. 1778 - 1781
(2020/03/11)
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- Iron powder and tin/tin chloride as new reducing agents of Meerwein arylation reaction with unexpected recycling to anilines
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Simple and rapid route for Meerwein arylation reaction using iron powder or a mixture of tin/tin chloride has been developed. In the presence of iron powder, different aryl diazonium salts reacted with methyl vinyl ketone, acrylates, and isopropenyl acetate. Production of oximes was detected as the main product with acrylates or in a mixture with β-aryl methyl ketones in the case of methyl vinyl ketone. The in situ produced HNO2 from an excess of NaNO2/HCl was trapped by alkyl aryl radical to form oximes in the E configuration form. The presence of tin/tin chloride mixture in the reaction of the aryl diazonium salts with methyl vinyl ketone produced Michael products along with β-aryl methyl ketones. The predicted α-aryl methyl ketones from the reaction of isopropenyl acetate with the diazotized anilines were obtained using iron or tin/tin chloride mixture.
- Abdelwahab, Ahmed B.,El-Sawy, Eslam R.,Kirsch, Gilbert
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supporting information
p. 526 - 538
(2020/01/08)
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- Nickel-Catalyzed Mono-Selective α-Arylation of Acetone with Aryl Chlorides and Phenol Derivatives
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The challenging nickel-catalyzed mono-α-arylation of acetone with aryl chlorides, pivalates, and carbamates has been achieved for the first time. A nickel/Josiphos-based catalytic system is shown to feature unique catalytic behavior, allowing the highly selective formation of the desired mono-α-arylated acetone. The developed methodology was applied to a variety of (hetero)aryl chlorides including biologically relevant derivatives. The methodology has been extended to the unprecedented coupling of acetone with phenol derivatives. Mechanistic studies allowed the isolation and characterization of key Ni0 and NiII catalytic intermediates. The Josiphos ligand is shown to play a key role in the stabilization of NiII intermediates to allow a Ni0/NiII catalytic pathway. Mechanistic understanding was then leveraged to improve the protocol using an air-stable NiII pre-catalyst.
- Amgoune, Abderrahmane,Derhamine, Sary Abou,Krachko, Tetiana,Monteiro, Nuno,Pilet, Guillaume,Schranck, Johannes,Tlili, Anis
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supporting information
p. 18948 - 18953
(2020/09/01)
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- Tandem Acid/Pd-Catalyzed Reductive Rearrangement of Glycol Derivatives
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Herein, we describe the acid/Pd-tandem-catalyzed transformation of glycol derivatives into terminal formic esters. Mechanistic investigations show that the substrate undergoes rearrangement to an aldehyde under [1,2] hydrogen migration and cleavage of an oxygen-based leaving group. The leaving group is trapped as its formic ester, and the aldehyde is reduced and subsequently esterified to a formate. Whereas the rearrangement to the aldehyde is catalyzed by sulfonic acids, the reduction step requires a unique catalyst system comprising a PdII or Pd0 precursor in loadings as low as 0.75 mol % and α,α′-bis(di-tert-butylphosphino)-o-xylene as ligand. The reduction step makes use of formic acid as an easy-to-handle transfer reductant. The substrate scope of the transformation encompasses both aromatic and aliphatic substrates and a variety of leaving groups.
- Ciszek, Benjamin,Fleischer, Ivana,Kathe, Prasad,Schmidt, Tanno A.
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supporting information
p. 3641 - 3646
(2020/03/25)
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- Transaminase-mediated synthesis of enantiopure drug-like 1-(3′,4′-disubstituted phenyl)propan-2-amines
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Transaminases (TAs) offer an environmentally and economically attractive method for the direct synthesis of pharmaceutically relevant disubstituted 1-phenylpropan-2-amine derivatives starting from prochiral ketones. In this work, we report the application of immobilised whole-cell biocatalysts with (R)-transaminase activity for the synthesis of novel disubstituted 1-phenylpropan-2-amines. After optimisation of the asymmetric synthesis, the (R)-enantiomers could be produced with 88-89% conversion and >99% ee, while the (S)-enantiomers could be selectively obtained as the unreacted fraction of the corresponding racemic amines in kinetic resolution with >48% conversion and >95% ee. This journal is
- Lakó, ágnes,Mendon?a, Ricardo,Molnár, Zsófia,Poppe, László
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p. 40894 - 40903
(2020/11/23)
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- One-Pot Transformation of Ketoximes into Optically Active Alcohols and Amines by Sequential Action of Laccases and Ketoreductases or ω-Transaminases
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An enzymatic one-pot process for asymmetric transformation of prochiral ketoximes into alcohols or amines was developed by sequential coupling of a laccase-catalyzed deoximation either with a ketone reduction (ketoreductase, KRED) or bioamination (ω-transaminase, ω-TA) in aqueous medium. An accurate selection of biocatalysts provided the corresponding products in excellent enantiomeric excesses and overall conversions ranging from 83 to >99 % for alcohols and 70 to >99 % for amines. Likewise, the employment of exclusively 1 % (w/w) of Cremophor, a polyethoxylated castor oil, as co-solvent enabled to reach concentrations up to 100 mM in the chiral alcohols cascade.
- Correia Cordeiro, Raquel S.,Ríos-Lombardía, Nicolás,Morís, Francisco,Kourist, Robert,González-Sabín, Javier
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p. 1272 - 1277
(2019/01/24)
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- Stereoselective Synthesis of 1-Arylpropan-2-amines from Allylbenzenes through a Wacker-Tsuji Oxidation-Biotransamination Sequential Process
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Herein, a sequential and selective chemoenzymatic approach is described involving the metal-catalysed Wacker-Tsuji oxidation of allylbenzenes followed by the amine transaminase-catalysed biotransamination of the resulting 1-arylpropan-2-ones. Thus, a series of nine optically active 1-arylpropan-2-amines were obtained with good to very high conversions (74–92%) and excellent selectivities (>99% enantiomeric excess) in aqueous medium. The Wacker-Tsuji reaction has been exhaustively optimised searching for compatible conditions with the biotransamination experiments, using palladium(II) complexes as catalysts and iron(III) salts as terminal oxidants in aqueous media. The compatibility of palladium/iron systems for the chemical oxidation with commercially available and made in house amine transaminases was analysed, finding ideal conditions for the development of a general and stereoselective cascade sequence. Depending on the selectivity displayed by selected amine transaminase, it was possible to produce both 1-arylpropan-2-amines enantiomers under mild reaction conditions, compounds that present therapeutic properties or can be employed as synthetic intermediates of chiral drugs from the amphetamine family. (Figure presented.).
- González-Martínez, Daniel,Gotor, Vicente,Gotor-Fernández, Vicente
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supporting information
p. 2582 - 2593
(2019/05/15)
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- Mild Iridium-Catalysed Isomerization of Epoxides. Computational Insights and Application to the Synthesis of β-Alkyl Amines
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The isomerization of epoxides to aldehydes using the readily available Crabtree's reagent is described. The aldehydes were transformed into synthetically useful amines by a one-pot reductive amination using pyrrolidine as imine-formation catalyst. The reactions worked with low catalyst loadings in very mild conditions. The procedure is operationally simple and tolerates a wide range of functional groups. A DFT study of its mechanism is presented showing that the isomerization takes place via an iridium hydride mechanism with a low energy barrier, in agreement with the mild reaction conditions. (Figure presented.).
- Cabré, Albert,Cabezas-Giménez, Juanjo,Sciortino, Giuseppe,Ujaque, Gregori,Verdaguer, Xavier,Lledós, Agustí,Riera, Antoni
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supporting information
p. 3624 - 3631
(2019/07/10)
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- Peroxygenase-Catalysed Epoxidation of Styrene Derivatives in Neat Reaction Media
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Biocatalytic oxyfunctionalisation reactions are traditionally conducted in aqueous media limiting their production yield. Here we report the application of a peroxygenase in neat reaction conditions reaching product concentrations of up to 360 mM.
- Alcalde, Miguel,Arends, Isabel W. C. E.,Hollmann, Frank,Paul, Caroline E.,Rauch, Marine C. R.,Tieves, Florian
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- Synthesis of β-Amino Diaryldienones Using the Mannich Reaction
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The Mannich reaction has been used for decades to prepare many pharmaceutically important molecules. Here, using a "double-Mannich-β-elimination" synthetic sequence, we report the synthesis and the characterization details of a novel class of β-amino diaryldienones with prominent antiprostate cancer activity. Through these studies, we correct an erroneous structure in the current literature, present a discussion of the stereochemical outcome of a new reaction, and probe the mechanism(s) of byproduct formation through isotopic studies.
- Elshan, N. G. R. Dayan,Rettig, Matthew B.,Jung, Michael E.
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supporting information
(2019/06/13)
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- Aerobic Oxidation of Secondary Alcohols with Nitric Acid and Iron(III) Chloride as Catalysts in Fluorinated Alcohol
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Fluorinated alcohols as solvents strongly influence and direct chemical reaction through donation of strong hydrogen bonds while being weak acceptors. We used 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as the activating solvent for a nitric acid and FeCl3-catalyzed aerobic oxidation of secondary alcohols to ketones. Reaction proceeded selectively with excellent yields with no reaction on the primary alcohol group. Oxidation of benzyl alcohols proceeds selectively to aldehydes with only HNO3 as the catalyst, while reaction on tertiary alcohols proceeds through dehydration and dimerization. A mechanistic study showed in situ formation of NOCl that converts alcohol into alkyl nitrite, which in the presence of Fe3+ ions and fluorinated alcohol decomposes into ketone. The study indicates that iron(III) acts also as the single-electron transfer catalyst in regeneration of NOCl reactive species.
- Mo?ina, ?tefan,Iskra, Jernej
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p. 14579 - 14586
(2019/11/14)
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- Catalytic oxidation of alcohols using Fe-bTAML and NaClO: Comparing the reactivity of Fe(V)O and Fe(IV)O intermediates
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We demonstrate the selective oxidation of secondary alcohols and activated primary alcohols to their corresponding aldehydes or ketones using Fe-bTAML as the catalyst and sodium hypochlorite (NaClO) as the oxidant. Good to excellent yields of 80%–99% for the carbonyl compounds and turnover numbers up to ～500 was obtained with this catalytic system. The reactions are clean, performed under mild conditions (air, room temperature) and yielded sodium chloride as the only by-product. The yield and turnover number were dependent on the pH of the reaction and this difference was attributed to the different reactive intermediates that was formed at pH 7 and pH 12 (FeV(O) and FeIV(O) respectively). Reactions involving the FeV(O) intermediate oxidize secondary alcohols more efficiently than its FeIV(O) analog. This trend was reversed for the oxidation of activated primary alcohols where reactions involving FeIV(O) afforded much higher TON's. This reactivity trend can be explained from the differences in bond dissociation energy (BDE) of their corresponding one electron reduced species ([FeIV-OH], ～99 kcal/mol; [FeIII-OH], ～83 kcal/mol) as well as their relative stabilities in the solvent during reaction. This catalytic system was found to be unsuitable for nonconjugated primary alcohol due to the formation of the inactive FeIV(OMe) intermediate after one catalytic cycle.
- Jana, Sandipan,Thomas, Jithin,Sen Gupta, Sayam
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p. 476 - 482
(2018/11/23)
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- Controllable construction of isoquinolinedione and isocoumarin scaffolds: Via RhIII-catalyzed C-H annulation of N -tosylbenzamides with diazo compounds
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A highly efficient protocol for the synthesis of isoquinolinediones by RhIII-catalyzed C-H activation/annulation/decarboxylation of N-tosylbenzamides with diazo compounds is reported. The switchable synthesis of isocoumarins was also achieved successfully via C-H activation/annulation with slight modification of the reaction conditions. Importantly, the synthetic utility of this new reaction was further demonstrated in an atom-economical and operationally convenient total synthesis of a TDP2 inhibitor derivative from commercially available starting materials.
- Liu, Yanfei,Wu, Jiaping,Qian, Baiyang,Shang, Yongjia
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supporting information
p. 8768 - 8777
(2019/10/16)
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- 1-aryl-2-acetone compound preparation method
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The invention discloses a 1-aryl-2-acetone compound preparation method, which comprises: (1) carrying out a reaction on (E)-2-methyl-3-aryl acrylic acid (I) as a starting raw material and diphenyl azidophosphate (DPPPA) in the presence of an organic alkali; (2) carrying out a heating reaction; and (3) adding an acidic aqueous solution into the reaction solution, and carrying out a reaction to obtain the 1-aryl-2-acetone compound with a structural formula (IV). According to the present invention, the method can solve the technical problems of difficultly available, highly-corrosive, highly toxic and highly explosive reagents, long steps, low yield, tedious operation and the like in the 1-aryl-2-acetone synthesis in the prior art, has characteristics of easily available raw materials, safe and simple operation, mild condition and high yield, and is suitable for industrial production.
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Paragraph 0037-0038
(2020/01/08)
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- Epoxidation of Cyclooctene Using Water as the Oxygen Atom Source at Manganese Oxide Electrocatalysts
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Epoxides are useful intermediates for the manufacture of a diverse set of chemical products. Current routes of olefin epoxidation either involve hazardous reagents or generate stoichiometric side products, leading to challenges in separation and significant waste streams. Here, we demonstrate a sustainable and safe route to epoxidize olefin substrates using water as the oxygen atom source at room temperature and ambient pressure. Manganese oxide nanoparticles (NPs) are shown to catalyze cyclooctene epoxidation with Faradaic efficiencies above 30%. Isotopic studies and detailed product analysis reveal an overall reaction in which water and cyclooctene are converted to cyclooctene oxide and hydrogen. Electrokinetic studies provide insights into the mechanism of olefin epoxidation, including an approximate first-order dependence on the substrate and water and a rate-determining step which involves the first electron transfer. We demonstrate that this new route can also achieve a cyclooctene conversion of ～50% over 4 h.
- Jin, Kyoungsuk,Maalouf, Joseph H.,Lazouski, Nikifar,Corbin, Nathan,Yang, Dengtao,Manthiram, Karthish
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supporting information
p. 6413 - 6418
(2019/05/02)
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- Regio- and chemoselective rearrangement of terminal epoxides into methyl alkyl and aryl ketones
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The development of the highly active pincer-type rhodium catalyst 2 for the nucleophilic Meinwald rearrangement of functionalised terminal epoxides into methyl ketones under mild conditions is presented. An excellent regio- and chemoselectivity is obtained for the first time for aryl oxiranes.
- Tian, Yingying,Jürgens, Eva,Kunz, Doris
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supporting information
p. 11340 - 11343
(2018/10/31)
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