- Ni-Catalyzed Aryl Sulfide Synthesis through an Aryl Exchange Reaction
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A Ni-catalyzed aryl sulfide synthesis through an aryl exchange reaction between aryl sulfides and a variety of aryl electrophiles was developed. By using 2-pyridyl sulfide as a sulfide donor, this reaction achieved the synthesis of aryl sulfides without using odorous and toxic thiols. The use of a Ni/dcypt catalyst capable of cleaving and forming aryl-S bonds was important for the aryl exchange reaction between 2-pyridyl sulfides and aryl electrophiles, which include aromatic esters, arenol derivatives, and aryl halides. Mechanistic studies revealed that Ni/dcypt can simultaneously undergo oxidative additions of aryl sulfides and aromatic esters, followed by ligand exchange between the generated aryl-Ni-SR and aryl-Ni-OAr species to furnish aryl exchanged compounds.
- Isshiki, Ryota,Kurosawa, Miki B.,Muto, Kei,Yamaguchi, Junichiro
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supporting information
p. 10333 - 10340
(2021/07/21)
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- Electrophilic Chlorine from Chlorosulfonium Salts: A Highly Chemoselective Reduction of Sulfoxides
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Herein, we describe a selective late-stage deoxygenation of sulfoxides based on a novel application of chlorosulfonium salts and demonstrate a new process using these species generated in situ from sulfoxides as the source of electrophilic chlorine. The use of highly nucleophilic 1,3,5-trimethoxybenzene (TMB) as the reducing agent is described for the first time and applied in the deoxygenation of simple and functionalized sulfoxides. The method is easy to handle, economic, suitable for gram-scale operations, and readily applied for poly-functionalized molecules, as demonstrated with more than 45 examples, including commercial medicines and analogues. We also report the results of competition experiments that define the more reactive sulfoxide and we present a mechanistic proposal based on substrate and product observations.
- Acosta-Guzmán, Paola,Mahecha-Mahecha, Camilo,Gamba-Sánchez, Diego
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supporting information
p. 10348 - 10354
(2020/07/13)
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- Preparation of flavin-containing mesoporous network polymers and their catalysis
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Riboflavin tetramethacrylate (RFlTMA) was prepared as a flavin monomer and copolymerized with ethylene glycol dimethacrylate (EGDMA) under polymerization-induced phase separation conditions. The resulting flavin-containing mesoporous network polymer, poly(RFlTMA-co-EGDMA), was found to be a more effective catalyst than riboflavin tetraacetate (RFlTA), a soluble analogue, for aerobic hydrogenation of olefins despite its heterogeneity, which allowed for its multiple recovery and reuse through simple filtrations and washings without loss in catalytic activity. In addition, the polymeric flavin was demonstrated to be utilized also as an effective photocatalyst in the oxidation of benzyl alcohols.
- Arakawa, Yukihiro,Sato, Fumiaki,Ariki, Kenta,Minagawa, Keiji,Imada, Yasushi
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supporting information
(2020/02/15)
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- Palladium complex containing meta-position carborane triazole ligand and preparation method and application of palladium complex
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The invention relates to a palladium complex containing a meta-position carborane triazole ligand and a preparation method and application of the palladium complex. The palladium complex is prepared by the following steps: (1) dropwise adding an n-BuLi solution into a meta-position carborane m-C2B10H12 solution, carrying out stirring and reacting, then adding 3-propargyl bromide for a reaction again, and after the reaction is finished, carrying out separating to obtain 1,3-dipropargyl meta-carborane; and (2) under the catalytic condition of a catalyst CuI, carrying out a reaction on 1,3-dipropargyl meta-carborane and aryl azide, then adding PdCl2 into a reaction system, continuing the reaction, and after the reaction is finished, carrying out separation to obtain the palladium complex containing the meta-carborane triazole ligand. Compared with the prior art, the preparation method provided by the invention is simple and green; the complex can efficiently catalyze a coupling reaction of mercaptan and halogenated hydrocarbon to synthesize thioether compounds; reaction conditions are mild, substrate universality is good, catalytic efficiency is high, and few byproducts are produced;and the catalyst has high stability and is not sensitive to air and water.
- -
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Paragraph 0041-0043
(2020/08/07)
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- Phosphine-free cobalt pincer complex catalyzed: Z -selective semi-hydrogenation of unbiased alkynes
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Herein, we report a novel, molecularly defined NNN-type cobalt pincer complex catalyzed transfer semi-hydrogenation of unbiased alkynes to Z-selective alkenes. This unified process is highly stereo- and chemo-selective and exhibits a broad scope as well as wide functional group tolerance. Ammonia-borane (AB), a bench-stable substrate with high gravimetric hydrogen capacity, was used as a safe and practical transfer hydrogenating source.
- Landge, Vinod G.,Pitchaimani, Jayaraman,Midya, Siba P.,Subaramanian, Murugan,Madhu, Vedichi,Balaraman, Ekambaram
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p. 428 - 433
(2018/02/07)
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- COBALT COMPLEXES, PROCESS FOR PREPARATION AND USE THEREOF
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The present invention discloses a cobalt compound of formula (I), a process for the preparation and use thereof. The present invention further relates to a pharmaceutical composition and a method inhibition of Tau Aggregation in a subject in need thereof using compound of formula (I).
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Page/Page column 17; 18
(2019/01/06)
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- Metal–organic framework MOF-199-catalyzed direct and one-pot synthesis of thiols, sulfides and disulfides from aryl halides in wet polyethylene glycols (PEG 400)
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A highly porous metal–organic frame work Cu3 BTC2 (copper(II)-benzene-1,3,5-tricarboxylate) that is known as MOF-199 was synthesized from the reaction of 1,3,5-benzenetricarboxylic acid and Cu(OAc)2·H2O by a solvothermal method and characterized by several techniques including FT-IR, XRD, EDX and scanning electron microscopy. The MOF-199 used as an efficient catalyst for one-pot synthesis of thiols by domino reactions of aryl halides and thiourea, and subsequently conversion to aryl alkyl sulfides and diaryl disulfides in polyethylene glycols (PEGs). A variety of aryl alkyl sulfides can be obtained in good to excellent yields in a relatively short reaction time and in the presence of the trace amount of catalyst. Also, the catalyst can be separated from the reaction mixture by decanting, and be reused without significant degradation in catalytic activity.
- Soleiman-Beigi, Mohammad,Sadeghizadeh, Fatemeh,Basereh, Ali
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p. 572 - 583
(2017/09/27)
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- Metal Nanoparticles Catalyzed Selective Carbon-Carbon Bond Activation in the Liquid Phase
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Understanding the C-C bond activation mechanism is essential for developing the selective production of hydrocarbons in the petroleum industry and for selective polymer decomposition. In this work, ring-opening reactions of cyclopropane derivatives under hydrogen catalyzed by metal nanoparticles (NPs) in the liquid phase were studied. 40-atom rhodium (Rh) NPs, encapsulated by dendrimer molecules and supported in mesoporous silica, catalyzed the ring opening of cyclopropylbenzene at room temperature under hydrogen in benzene, and the turnover frequency (TOF) was higher than other metals or the Rh homogeneous catalyst counterparts. Comparison of reactants with various substitution groups showed that electron donation on the three-membered ring boosted the TOF of ring opening. The linear products formed with 100% selectivity for ring opening of all reactants catalyzed by the Rh NP. Surface Rh(0) acted as the active site in the NP. The capping agent played an important role in the ring-opening reaction kinetics. Larger particle size tended to show higher TOF and smaller reaction activation energy for Rh NPs encapsulated in either dendrimer or poly(vinylpyrrolidone). The generation/size of dendrimer and surface group also affected the reaction rate and activation energy.
- Ye, Rong,Yuan, Bing,Zhao, Jie,Ralston, Walter T.,Wu, Chung-Yeh,Unel Barin, Ebru,Toste, F. Dean,Somorjai, Gabor A.
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p. 8533 - 8537
(2016/07/26)
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- Symbiotic Transition-Metal and Organocatalysis for Catalytic Ambient Amine Oxidation and Alkene Reduction Reactions
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A new oxidation reaction based on two simple catalysts, namely, alloxan and a CuI salt, is highly effective for the aerobic oxidation and oxidative cross-coupling of amines. The reaction is operationally simple, reaction atmospheres enriched in dioxygen are obviated, and neither catalyst component requires prior synthesis. Mechanistic investigations have been performed and point towards a complex reaction manifold with evidence that supports a catalytic cycle that does not proceed through a quinone-imine step. Additionally, this dual catalyst system is efficient to effect diimide-mediated hydrogenation reactions of alkenes and alkynes, a transformation that has not been reported previously in the context of quinone catalyst systems.
- Murray, Alexander T.,King, Rose,Donnelly, Joseph V. G.,Dowley, Myles J. H.,Tuna, Floriana,Sells, Daniel,John, Matthew P.,Carbery, David R.
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p. 510 - 514
(2016/02/20)
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- Transition-Metal-Free Coupling of Alkynes with α-Bromo Carbonyl Compounds: An Efficient Approach towards β,γ-Alkynoates and Allenoates
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A direct transition-metal-free coupling between alkynes and α-bromo carbonyl compounds has been developed with ultraviolet (UV) light in aqueous media. This method represents a facile approach to synthetically useful β,γ-alkynyl esters and amides stereoselectively from two readily available starting materials. As an example of the synthetic application of the products, the alkynyl esters were readily converted into allenoates. Time for UV! A direct coupling between alkynes and α-bromo compounds has been developed with ultraviolet light in aqueous media (see scheme). This method represents a facile approach to synthetically useful β,γ-alkynyl esters and amides stereoselectively from two readily available starting materials.
- Liu, Wenbo,Chen, Zhengwang,Li, Lu,Wang, Haining,Li, Chao-Jun
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supporting information
p. 5888 - 5893
(2016/04/26)
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- Enhanced Reactivity of Aerobic Diimide Olefin Hydrogenation with Arylboronic Compounds: An Efficient One-Pot Reduction/Oxidation Protocol
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A catalyst-free and efficient method for simultaneous olefin hydrogenation and oxidation of arylboronate esters to phenols with hydrazine hydrate and molecular oxygen is presented. The process is based on the utilization of a readily available Lewis acidic arylboron compound, which evades common problems associated with the catalyst-free aerobic hydrogenation of olefins with diimide. Using an operationally simple procedure, the protocol smoothly delivers phenol derivatives and various alkanes in excellent yields with remarkable functional group compatibility. The method allows the reaction to be scaled up to 1 g of the starting materials.
- Santra, Surojit,Guin, Joyram
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supporting information
p. 7253 - 7257
(2015/11/25)
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- Continuous flow reduction of artemisinic acid utilizing multi-injection strategies - Closing the gap towards a fully continuous synthesis of antimalarial drugs
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One of the rare alternative reagents for the reduction of carbon-carbon double bonds is diimide (HN=NH), which can be generated in situ from hydrazine hydrate (N2H4·H2O) and O2. Although this selective method is extremely clean and powerful, it is rarely used, as the rate-determining oxidation of hydrazine in the absence of a catalyst is relatively slow using conventional batch protocols. A continuous high-temperature/high-pressure methodology dramatically enhances the initial oxidation step, at the same time allowing for a safe and scalable processing of the hazardous reaction mixture. Simple alkenes can be selectively reduced within 10-20 min at 100-120°C and 20 bar O2 pressure. The development of a multi-injection reactor platform for the periodic addition of N2H4·H2O enables the reduction of less reactive olefins even at lower reaction temperatures. This concept was utilized for the highly selective reduction of artemisinic acid to dihydroartemisinic acid, the precursor molecule for the semisynthesis of the antimalarial drug artemisinin. The industrially relevant reduction was achieved by using four consecutive liquid feeds (of N2H4·H2O) and residence time units resulting in a highly selective reduction within approximately 40 min at 60°C and 20 bar O2 pressure, providing dihydroartemisinic acid in ≥93% yield and ≥95% selectivity.
- Pieber, Bartholom?us,Glasnov, Toma,Kappe, C. Oliver
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supporting information
p. 4368 - 4376
(2015/03/14)
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- NaI/silica sulfuric acid as an efficient reducing system for deoxygenation of sulfoxides in poly ethylene glycol (PEG-200)
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Deoxygenation of structurally diverse sulfoxides including dialkyl, diaryl, aryl alkyl and allyl sulfoxides to the corresponding sulfides were carried out using a NaI/silica sulfuric acid reducing system at room temperature in poly ethylene glycol (PEG-200) in excellent yields.
- Zarei, Morteza,Ameri, Mohammad Aghil,Jamaleddini, Azar
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p. 259 - 263
(2013/08/26)
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- Enantioselective nitrene transfer to sulfides catalyzed by a chiral iron complex
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Iron works: Enantioselective nitrene transfer to sulfide was accomplished by a chiral iron(III)/PyBOX catalyst (see scheme). Various sulfimides were thus obtained in high enantioselectivities and yields. Applications of this protocol to the syntheses of enantioenriched sulfoximines and an epoxide were also demonstrated. Copyright
- Wang, Jun,Frings, Marcus,Bolm, Carsten
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supporting information
p. 8661 - 8665
(2013/09/12)
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- Gas-phase S-alkylation of benzenethiol with aliphatic alcohols, ethers, esters, alkyl halides and olefins over halide cluster catalysts of Groups 5 and 6 transition metals
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Benzenethiol was reacted with methanol under a hydrogen stream over [(Nb6Cl12)Cl2(H2O) 4]·6H2O supported on silica gel. Catalytic activity of the cluster commenced above 250 °C, yielding methyl phenyl sulfide. The selectivity was 98% at 400 °C. Molybdenum, tantalum and tungsten halide clusters with the same octahedral metal framework also catalyzed the reaction. Primary alcohols with shorter alkyl chains were effective reagents for the S-alkylation. Aliphatic ethers, dialkyl carbonates, orthoesters and alkyl halides were effective reagents for the S-alkylation. When 1-hexene was applied to the reaction, spontaneous and catalytic S-alkylation proceeded simultaneously above 200 °C, yielding n-hexyl phenyl sulfide. When alkyl acetates were subjected to this reaction, the niobium cluster afforded S-phenyl thioacetate, and the other clusters afforded alkyl phenyl sulfides selectively. A Br?nsted acid site attributable to a hydroxo ligand, which is formed on the cluster complex by thermal activation, is proposed as the active site of the catalysts.
- Nagashima, Sayoko,Kudo, Kentaro,Yamazaki, Hitomi,Kamiguchi, Satoshi,Chihara, Teiji
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- In situ generation of diimide from hydrazine and oxygen: Continuous-flow transfer hydrogenation of olefins
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No catalyst required! A highly efficient, catalyst-free process to generate diimide in situ from hydrazine monohydrate and molecular oxygen for the selective reduction of alkenes has been developed. The use of a gas-liquid segmented flow system allowed safe operating conditions and dramatically enhanced this atom-economical reaction, resulting in short processing times. Copyright
- Pieber, Bartholomaeus,Martinez, Sabrina Teixeira,Cantillo, David,Kappe, C. Oliver
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supporting information
p. 10241 - 10244
(2013/10/21)
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- Reduction of alkenes catalyzed by copper nanoparticles supported on diamond nanoparticles
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Copper nanoparticles (Cu NPs) supported on diamond nanoparticles (D NPs) previously purified by Fenton treatment (Cu/D) followed by annealing with hydrogen (Cu/DH) are highly efficient and reusable heterogeneous catalysts for hydrogenation of styrene to ethylbenzene with the minimum productivity value of 30617 cycles. The Royal Society of Chemistry.
- Dhakshinamoorthy, Amarajothi,Navalon, Sergio,Sempere, David,Alvaro, Mercedes,Garcia, Hermenegildo
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supporting information
p. 2359 - 2361
(2013/07/05)
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- Iron(III) chloride-catalysed aerobic reduction of olefins using aqueous hydrazine at ambient temperature
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A chemoselective reduction of olefins and acetylenes is demonstrated by employing catalytic amounts of ferric chloride hexahydrate (FeCl 3·6 H2O) and aqueous hydrazine (NH 2NH2·H2O) as hydrogen source at room temperature. The reduction is chemoselective and tolerates a variety of reducible functional groups. Unlike other metal-catalysed reduction methods, the present method employs a minimum amount of aqueous hydrazine (1.5-2 equiv.). Also, the scope of this method is demonstrated in the synthesis of ibuprofen in aqueous medium. Copyright
- Lamani, Manjunath,Ravikumara, Guralamata S.,Prabhu, Kandikere Ramaiah
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supporting information; experimental part
p. 1437 - 1442
(2012/07/03)
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- Guanidine catalyzed aerobic reduction: A selective aerobic hydrogenation of olefins using aqueous hydrazine
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An efficient aerobic reduction of olefins, internal as well as terminal, is developed using guanidine as an organocatalyst. A remarkable chemoselectivity in reduction has been demonstrated in the presence of a variety of functional groups and protective groups and a selective reduction of a terminal olefin in the presence of an internal olefin is revealed.
- Lamani, Manjunath,Guralamata, Ravikumara Siddappa,Prabhu, Kandikere Ramaiah
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supporting information; experimental part
p. 6583 - 6585
(2012/07/14)
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- Aerobic reduction of olefins by in situ generation of diimide with synthetic flavin catalysts
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A versatile reducing agent, diimide, can be generated efficiently by the aerobic oxidation of hydrazine with neutral and cationic synthetic flavin catalysts 1 and 2. This technique provides a convenient and safe method for the aerobic reduction of olefins, which proceeds with 1 equiv of hydrazine under an atmosphere of O2 or air. The synthetic advantage over the conventional gas-based method has been illustrated through high hydrazine efficiency, easy and safe handling, and characteristic chemoselectivity. Vitamin B2 derivative 6 acts as a highly practical, robust catalyst for this purpose because of its high availability and recyclability. Association complexes of 1b with dendritic 2,5-bis(acylamino)pyridine 15 exhibit unprecedented catalytic activities, with the reduction of aromatic and hydroxy olefins proceeding significantly faster when a higher-generation dendrimer is used as a host pair for the association catalysts. Contrasting retardation is observed upon similar treatment of non-aromatic or non-hydroxy olefins with the dendrimer catalysts. Control experiments and kinetic studies revealed that these catalytic reactions include two independent, anaerobic and aerobic, processes for the generation of diimide from hydrazine. Positive and negative dendrimer effects on the catalytic reactions have been ascribed to the specific inclusion of hydrazine and olefinic substrates into the enzyme-like reaction cavities of the association complex catalysts. Copyright
- Imada, Yasushi,Iida, Hiroki,Kitagawa, Takahiro,Naota, Takeshi
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scheme or table
p. 5908 - 5920
(2011/07/07)
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- A simple and efficient method for reduction of sulfoxide under solvent-free conditions
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Benzyl DABCO bromide was found to be an efficient and mild reagent for the reduction of sulfoxides to the corresponding sulfide using sulfuric acid adsorbed silica gel under solvent-free conditions at room temperature.
- Pourmousavi, Seied Ali,Salehi, Parvin
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experimental part
p. 803 - 807
(2010/07/08)
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- Neutral flavins: Green and robust organocatalysts for aerobic hydrogenation of olefins
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"Chemical Equation Presented" Various olefins can be hydrogenated quantitatively with neutral flavin 2 catalysts in the presence of 1 -2 equiv of hydrazine under 1 atm of O2. Vitamin B2 derivative 2g acts as a highly efficient and robust catalyst for the present environmentally benign process producing water and nitrogen gas as the only waste products
- Imada, Yasushi,Kitagawa, Takahiro,Ohno, Takashi,Iida, Hiroki,Naota, Takeshi
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supporting information; experimental part
p. 32 - 35
(2010/03/04)
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- One-pot o-nitrobenzenesulfonylhydrazide (NBSH) formation-diimide alkene reduction protocol
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A one-pot protocol for the formation of 2-nitrobenzenesulfonylhydrazide (NBSH) from commercial reagents and subsequent alkene reduction is presented. The transformation is operationally simple and generally efficient for effecting diimide alkene reductions. A range of 16 substrates have been reduced, highlighting the unique chemoselectivity of diimide as a reduction system.
- Marsh, Barrie J.,Carbery, David R.
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supporting information; experimental part
p. 3186 - 3188
(2009/09/08)
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- Partial hydrogenation of alkynes to cis-olefins by using a novel Pd 0-polyethyleneimine catalyst
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The creation and application of a new Pd0-polyethyleneimine complex catalyst (Pd0-PEI) was investigated. The 55 Pd 0-PEI catalyst was prepared by introduction of Pd(OAc)2 directly in the MeOH solution of deaerated PEI under Ar atmosphere. Reactions were carried out using 10 weight % versus substrate of 5% Pd0-PEI in 2mL solvent under H2 atmosphere at room temperature. The generality of the process was shown by disubstituting alkynes. Even for the substrate bearing a conjugated ketone on the alkyne, the serious over-reduction was not observed while significant cistrans isomerization of methyl styryl ketone accompanied the partial hydrogenation on the basis of keto-enol tautomerism. Pd0-PEI catalyst is also applicable to the partial hydrogenation of monosubstituted alkynes to monosubstituted olefins.
- Sajiki, Hironao,Mori, Shigeki,Ohkubo, Tomoyuki,Ikawa, Takashi,Kume, Akira,Maegawa, Tomohiro,Monguchi, Yasunari
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supporting information; experimental part
p. 5109 - 5111
(2009/05/07)
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- Reduction of carbon-carbon double bonds using organocatalytically generated diimide
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(Chemical Equation Presented) An efficient method has been developed for the reduction of carbon-carbon double bonds with diimide, catalytically generated in situ from hydrazine hydrate. The employed catalyst is prepared in one step from riboflavin (vitamin B2). Reactions are carried out in air and are a valuable alternative when metal-catalyzed hydrogenations are problematic.
- Smit, Christian,Fraaije, Marco W.,Minnaard, Adriaan J.
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supporting information; experimental part
p. 9482 - 9485
(2009/04/06)
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- Clay entrapped nickel nanoparticles as efficient and recyclable catalysts for hydrogenation of olefins
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Nickel nanoparticles are prepared in the interlamellar spaces of K10-Montmorillonite clay by chemical reduction at moderate temperatures. These clay entrapped nickel nanoparticles are characterized by UV-vis, powder XRD, EDX and HRTEM studies. The resultant ecofriendly supramolecular assembly with nickel content (2.84 wt %) has good catalytic efficiency in hydrogenation of alkenes and alkynes with hydrazine as a reducing agent in ethanol medium. Advantages of the present study include absence of an external hydrogen source, catalyst reusability and a green medium.
- Dhakshinamoorthy, Amarajothi,Pitchumani, Kasi
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p. 1818 - 1823
(2008/09/18)
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- Hydrogen-free homogeneous catalytic reduction of olefins in aqueous solutions
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(Chemical Equation Presented) Herein we report a study involving the homogeneous catalytic reduction of unsaturated substrates in aqueous solutions or water-organic solvent mixtures. The reduction of olefins has been carried out in the presence of catalytic amounts of [Fe(CN)5NH3] 3- and excess of NH2OH, which under mild reaction conditions can be used to reduce carbon-carbon unsaturations without affecting carbonyl functionalities and aromatic rings. To explore the scope of the catalytic reduction, a wide variety of representative unsaturated substrates have been examined. The steric effects of the substituents on the carbon-carbon multiple bond as well as the regioselectivity and stereoselectivity of the catalyst have been studied. The deuterium kinetic isotope effect on the catalytic reduction of double bonds in olefins has been analyzed, and no significant kinetic isotope effect was found. Among the great advantages of this novel procedure for catalytic reduction are that hydrogen and high pressures are not needed, the catalyst is inexpensive and easily prepared, and water as well as water-organic solvent mixtures can be used as reaction media.
- Gaviglio, Carina,Doctorovich, Fabio
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p. 5379 - 5384
(2008/12/20)
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- Sulfite-promoted one-pot synthesis of sulfides by reaction of aryl disulfides with alkyl halides
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A sodium dithionite, sodium thiosulfate and rongalite promoted one-pot synthesis of aryl alkyl sulfides at room temperature has been developed. The reactions of a range of disulfides with alkyl halides proceeded smoothly in the presence of rongalite. Possible reaction pathways are discussed and the effects of these sulfites on disulfides are investigated. The important features of this protocol are metal-free, strong-base-free, and mild reaction conditions, operational simplicity, short reaction times and high yields of products. Georg Thieme Verlag Stuttgart.
- Tang, Ri-Yuan,Zhong, Ping,Lin, Qiu-Lian
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- Catalytic asymmetric hydroboration of heterofunctional allylic substrates: an efficient heterogenized version
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The hydroboration of heterofunctional allylic systems with catecholborane (HBcat) using neutral and cationic rhodium complexes modified with P-P and P-N bidentate chiral ligands has been described in order to produce the secondary heteroorganoboronate ester as a major product with moderate enantioselectivity. The immobilization of cationic chiral rhodium complexes onto clays has beneficial effects on the recyclability and reuse of the catalytic system in particular for the hydroboration of allyl aryl sulfones.
- Lillo, Vanesa,Fernandez, Elena,Segarra, Anna M.
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p. 911 - 914
(2008/02/03)
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- A mild and efficient copper-catalyzed coupling of aryl iodides and thiols using an oxime-phosphine oxide ligand
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A mild and efficient copper-catalyzed system for the coupling of aryl iodides and thiols was developed using a readily prepared and highly stable oxime-phosphine oxide ligand. Good to excellent yields were obtained.
- Zhu, Di,Xu, Lei,Wu, Fan,Wan, Boshun
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p. 5781 - 5784
(2007/10/03)
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- KF/Al2O3-mediated N-alkylation of amines and nitrogen heterocycles and S-alkylation of thiols
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KF/Al2O3 efficiently catalyzes N-alkylation of heterocyclic, primary, and secondary amines and S-alkylation of thiols with a variety of alkyl halides. The N-alkylation and S-alkylation adducts were produced in good to excellent yields and in short times. Copyright Taylor & Francis Group, LLC.
- Moghaddam, Firouz Matloubi,DokhtTaimoory, Seyedeh Maryam,Ismaili, Hossein,Bardajee, Ghasem Rezanejade
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p. 3599 - 3607
(2007/10/03)
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- Deoxygenation of sulfoxides and reductive coupling of sulfonyl chlorides, sulfinates and thiosulfonates using Silphos [PCl3-n(SiO 2)n] as a heterogeneous phosphine reagent
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Deoxygenation of sulfoxides to thioethers and reductive coupling of sulfonyl chlorides, sodium sulfinates and thiosulfonates to their corresponding disulfides were carried out by a heterogeneous phosphine reagent, Silphos [PCl3-n(SiO2)n] and molecular I2 in dry refluxing MeCN in high yields. Georg Thieme Verlag Stuttgart.
- Iranpoor, Nasser,Firouzabadi, Habib,Jamalian, Arezu
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p. 1447 - 1449
(2007/10/03)
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- Flavin-catalyzed generation of diimide: An environmentally friendly method for the aerobic hydrogenation of olefins
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The first green and practical method for "aerobic hydrogenation" involving the use of hydrazine and an organocatalyst is described. Olefins can be hydrogenated by treatment with hydrazine in the presence of a 5-ethyl-3-methyllumiflavinium perchlorate (FlEt+·ClO4-) catalyst under O2 atmosphere to give the corresponding hydrogenated products in excellent yields along with environmentally benign water and molecular nitrogen as the only waste products. Copyright
- Imada, Yasushi,Iida, Hiroki,Naota, Takeshi
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p. 14544 - 14545
(2007/10/03)
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- Nucleophilic substitution by Grignard reagents on sulfur mustards
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With proper activation of the leaving group, sulfur mustards react with Grignard reagents with neighboring group participation of the sulfur atom. 2,6-Dichloro-9-thiabicyclo[3.3.1]nonane is especially useful in this regard, providing clean reactivity with organomagnesium nucleophiles on a topologically constrained scaffold.
- Converse, Antonella,Saaidi, Pierre-Loic,Sharpless, K. Barry,Finn
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p. 7336 - 7339
(2007/10/03)
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- Application of alkoxy-λ6-sulfanenitriles as strong alkylating reagents
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Alkoxy-λ6-sulfanenitriles were found to be versatile alkylating reagents toward various nucleophiles bearing at least one proton such as methanol, phenol, thiophenols, carboxylic acids, ptoluenesulfonic acid, hydrochloric acid, and primary and secondary amines. Reactivity of the alkoxy group of the λ6-sulfanenitriles showed an opposite trend to the usual SN2 character, i.e. Me (la), Pr (1b), and Bu (1d) ? i-Pr (1c). In the presence of p-TsOH, alkyl tosylates were predominantly formed instead of the alkylation products of nucleophiles. In addition, even a sterically hindered substrate, neopentyloxy-λ6-sulfanenitrile, was found to undergo an SN2 reaction toward thiophenol without any rearrangement product to give neopentyl phenyl sulfide in good yield.
- Hao, Wei,Fujii, Takayoshi,Dong, Tiaoling,Wakai, Youko,Yoshimura, Toshiaki
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p. 193 - 198
(2007/10/03)
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- A new approach to the reduction of sulfoxides to sulfides with 1,3-dithiane in the presence of electrophilic bromine as catalyst
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A new, mild, and novel method is described for the efficient deoxygenation of sulfoxides to their corresponding sulfides with 1,3-dithiane at room temperature in the presence of catalytic amounts of N-bromosuccinimide (NBS), 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TABCO), or Br2 as the source of electrophilic bromine.
- Iranpoor, Nasser,Firouzabadi, Habib,Shaterian, Hamid Reza
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p. 2826 - 2830
(2007/10/03)
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- Co-C bond cleavage in the reactions of alkyl, benzyl and heteroaromaticmethyl cobaloximes with arene sulfenyl chloride: Homolytic and heterolytic pathways
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The reactions of arene sulfenyl chlorides, ArSCl, (Ar=Ph, C6Cl5, 2,4 (NO2)2C6H3) with organocobaloximes, RCo(dmgH)2Py, (R=alkyl, benzyl and heteroaromaticmethyl) were carried out under thermal and photochemical conditions. A variety of organic and organometallic products are formed depending upon the substrate cobaloxime. For 3-methoxybenzyl and heteroaromaticmethyl cobaloximes the results suggest that they represent a unique class of cobaloximes whereby both the aromatic ring as well as the Co-C bond are highly activated towards attack by the arene sulfenyl chloride. Both homolytic as well as heterolytic pathways are operative.
- Gupta,Dixit, Vandana,Das, Indira
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- Microwave assisted, highly efficient solid state N- and S-alkylation
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Secondary amines and thiophenols were alkylated with alkyl and benzyl halides rapidly on alumina supported potassium carbonate under solvent-free conditions using microwaves. Equimolar amounts of the secondary amine/thiophenol and alkyl halide were used. The procedure neither required any strong base nor a PTC Aniline was also monobenzylated with benzylchloride. Separation of the products from the reactants was very simple by using a nonpolar solvent for desorption.
- Jaisinghani, Harsha G.,Khadilkar, Bhushan M.
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p. 3693 - 3698
(2007/10/03)
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- Deoxygenation of sulfoxides and selenoxides with nickel boride
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The deoxygenations of a variety of acyclic sulfoxides and selenoxides have been reported with nickel boride in THF at 0-5°C in nearly quantitative yields. The deoxygenations are proposed to proceed by an oxidative-addition and reductive-elimination mechanism.
- Khurana, Jitender M.,Ray, Abhijit,Singh, Sarika
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p. 3829 - 3832
(2007/10/03)
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- γ-lodothioethers as a source of sulfurcontaining radicals: Reaction with electrophilic olefins
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The reaction of several y-iodothioethers (1) with different electrophilic olefins (2), tributyltin chloride and sodium borohydride in the presence of a catalytic amount of AIBN yielded, after treatment with a saturated aqueous solution of sodium fluoride, a mixture of the expected addition products (3) and the corresponding reduced thioethers (4), which can be easily separated chromatographically. Springer-Verlag Iberica 1996.
- Foubelo, Francisco,Gutierrez, Ana Maria
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p. 280 - 284
(2007/10/03)
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- Reductive α-substitution of sulfoxides with grignard reagents promoted by a magnesium amide
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The reactions of sulfoxides bearing α-hydrogen(s) (RSOCHR1R2: R-alkyl or aryl; R1, R2 = H, alkyl, or aryl) with Grignard reagents (R3MgBr: R3 = Et, Ph, or vinyl) in the presence of the diisopropylaminomagnesium reagent, generated in situ by the treatment of diisopropylamine with the appropriate Grignard reagents in diethyl ether, have resulted in the formation of the corresponding sulfides (RSCR1R2R3) in moderate to good isolated yields.
- Kobayashi, Kazuhiro,Yokota, Kouichi,Akamatsu, Hideki,Morikawa, Osamu,Konishi, Hisatoshi
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p. 441 - 443
(2007/10/03)
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- Low pressure hydrogenation of unsaturated sulphides with homogeneous and heterogeneous ruthenium catalysts
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Ru2O·nH2O and [Ru3O(AcO)6(H2O)3]+AcO- were examined for catalytic activity in the hydrogenation of a series of unsaturated sulphides under heterogeneous and homogeneous conditions, respectively. By the appropriate combination of these two methodologies, a number of saturated sulphides could be synthesized in satisfactory to good yields, thus minimizing side reactions.
- Cere, Vanda,Massaccesi, Franco,Pollicino, Salvatore,Ricci, Alfredo
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p. 899 - 907
(2007/10/03)
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- Diastereoselective radical alkylations of alkyl aryl sulfoxides
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1,2-Asymmetric induction in reactions of arylsulfinylated radicals has been examined and compared to the anionic processes. A rule of thumb allowing to predict the stereoselectivity is presented.
- Zahouily, Mohamed,Caron, Giulia,Carrupt, Pierre-Alain,Knouzi, Nourdine,Renaud, Philippe
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p. 8387 - 8390
(2007/10/03)
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- Photochemical recycling of polyarylene sulfide
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The selective degradation of polyarylene sulfide via soluble polysulfonium salts was employed to give the monomer.
- Tsuchida, Eishun,Yamamoto, Kimihisa,Shouji, Eiichi,Haryono, Agus
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p. 2091 - 2092
(2007/10/03)
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- The reduction of sulfoxides and active halides with Cp2TiCl2/Sm system
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Cp2TiCl2/Samarium system is used as a new reagent for reducing sulfoxides to sulfides, benzyl halides to bibenzyls and α-bromoketones to ketones respectively in good yields under mild and neutral conditions.
- Zhang,Yu,Bao
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p. 1825 - 1830
(2007/10/02)
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- Reactions of Sulfoxides with Magnesium Amides. Transformations of Sulfoxides into Sulfides, Dithioacetals and Vinyl Sulfides
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The reactions of sulfoxides with magnesium amides generated in situ from the reaction of ethylmagnesium bromide and seconday amines, such as diisopropylamine (DIPA) or 2,2,6,6-tetramethylpiperidine (TMP) in diethyl ether, were examined.Diaryl sulfoxides were heated with the diisopropylaminomagnesium reagent in diethyl ether to give the corresponding diaryl sulfides in 42-52percent yields.Sulfoxides bearing hydrogens at the α-position only(RSOCH2R1) reacted with the tetramethylpiperidinomagnesium reagent at room temperature to produce the corresponding dithioacetals (RSCHR1SR) in 47-86percent yields.The treatment of sulfoxides bearing hydrogens both at the α-and β-positions (RSOCHR1CHR2R3) with the magnesium amides at room temperature afforded the corresponding vinyl sulfides (RSCR1=CR2R3) in 52-72percent yields accompanying 2.3-27percent yields of the corresponding dithioacetals.The pathways leading to the products involving the formation of the sulfur-stabilized carbonium ion intermediates are discussed.
- Kobayashi, Kazuhiro,Kawakita, Masataka,Yokota, Kouichi,Mannami, Tohru,Yamamoto, Koji,et al.
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p. 1401 - 1408
(2007/10/02)
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- Tellurium(IV) chloride/sodium iodide mediated facile and mild reduction of sulphoxides to sulphides
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Tellurium(IV) chloride/sodium iodide reagent system reduces dialkyl, diaryl and alkylaryl sulphoxides to the corresponding sulphides in high yield in acetonitrile at room temperature.
- Khan, R H,Rastogi, R C
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p. 293 - 294
(2007/10/02)
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- A Selectivity Study of Activated Ketal Reduction with Borane Dimethyl Sulfide
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A chemo- and regioselectivity study of the reagent combination BH3*SMe2/TMSOTf for ketal reduction has been undertaken.It has revealed that simple 1,3-dioxanes reduce cleanly at low temperature in CH2Cl2 while simple 1,3-dioxolanes may give complete ring cleavage and dimerization products.A study of reduction of 4-substituted 1,3-dioxolanes has revealed a solvent-directed regioselectivity which in THF favors the secondary protected derivative.A mechanism is postulated to account for the selectivities based on recent thinking on acetal substitution reactions.
- Bartels, Birgit,Hunter, Roger
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p. 6756 - 6765
(2007/10/02)
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- Chemoselective alkylation of thiols: A detailed investigation of reactions of thiols with halides
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Arylthiols, aralkylthiols and alkane thiols can be readily alkylated by alkyl/aralkyl halides in presence of K2CO3/DMF to yield unsymmetrical sulphides in nearly quantitative yields. 2-Mercaptoethanol gave the thioether chemoselectively.
- Khurana,Sahoo
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p. 1691 - 1702
(2007/10/02)
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- Synthesis of 2-(Trimethylsilyl)ethyl Benzenesulfenate and Benzeneselenenate and Their Reaction with Some Electrophiles in the Presence of Tetrabutylammonium Fluoride
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2-(Trimethylsilyl)ethyl benzenesulfenate was allowed to react with several halides in the presence of tetrabutylammonium fluoride (TBAF) to afford the corresponding phenyl sulfoxides as the main product.In the reaction of 2-(trimethylsilyl)ethyl benzeneselenenate and several halides with TBAF, the corresponding alcohols were obtained as the main product.
- Oida, Tatsuo,Ohnishi, Atsushi,Shimamaki, Toshiharu,Hayashi, Yoshiyuki,Tanimoto, Shigeo
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p. 702 - 704
(2007/10/02)
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