- Novel access to carbonyl and acetylated compounds: The role of the tetra-: N -butylammonium bromide/sodium nitrite catalyst
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A novel aerobic oxidation of alcohols without the use of any oxidants was developed. An equimolar catalytic mixture of tetra-n-butylammonium bromide and sodium nitrite catalyzes the aerobic selective oxidation of benzylic alcohols under oxidant-free, base-free and metal-free conditions. The mild reaction conditions allow oxidation of a wide range of benzylic alcohols, chemo-selectively to their carbonyl compounds (68-93% isolated yields). More importantly, high selectivity among different kinds of alcohols (aromatic vs. aliphatic alcohols, primary vs. secondary alcohols as well as alcohols having neutral rings vs. electron-deficient rings) is available by this approach. The method surprisingly switched over to be an efficient acetylation approach in the case of aliphatic alcohols without the use of any transition metal, phosphorous or other toxic reagents or any need for using toxic acyl halides, sulfonyl halides, anhydrides, etc. by the use of only acetic acid as a reagent.
- Sheykhan, Mehdi,Moafi, Hadi Fallah,Abbasnia, Masoumeh
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p. 51347 - 51355
(2016/06/09)
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- Visible-light-promoted conversion of alkyl benzyl ether to alkyl ester or alcohol via O-α-sp3 C-H cleavage
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A mild and high-yielding visible-light-promoted conversion of alkyl benzyl ethers to the alkyl esters or alkyl alcohols was developed. Mechanistic studies provided evidence for a radical chain reaction involving the homolytic cleavage of O-α-sp3 C-H bonds in the substrate as one of the propagation steps. We propose that α-bromoethers are key intermediates in the transformation.
- Lu, Ping,Hou, Tianyuan,Gu, Xiangyong,Li, Pixu
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supporting information
p. 1954 - 1957
(2015/04/27)
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- Solvent-free transesterification in a ball-mill over alumina surface
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An efficient procedure for transesterification has been developed in a ball-mill in the absence of any solvent, acid/base or metal catalyst. A variety of methyl, ethyl, allyl esters have been transesterified to higher benzyl and other esters in high yields by this procedure.
- Chatterjee, Tanmay,Saha, Debasree,Ranu, Brindaban C.
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experimental part
p. 4142 - 4144
(2012/08/28)
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- Separation, recovery and reuse of N-heterocyclic carbene catalysts in transesterification reactions
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A novel and convenient strategy to separate, recover and reuse N-heterocyclic carbene catalysts in transesterification reactions has been developed.
- Zeng, Tieqiang,Song, Gonghua,Li, Chao-Jun
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supporting information; experimental part
p. 6249 - 6251
(2010/02/16)
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- Method for producing Suzuki coupling compound catalysed by a nickel compound
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There are disclosed a method for producing a cross-coupling compound of formula (3):(Y-)(n-1)R1-R2-(R1)(n'-L) ???wherein R1 represents ???a substituted or unsubstituted, linear, branched, or cyclic hydrocarbon group, and ???n and n' each represent 1 or 2, ???provided that when n and n' are the same, both n and n' are not 2, ???R2 represents a substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl or substituted or unsubstituted alkenyl group, ???and ???Y represents R2 or X1, wherein R2 is as defined above, and X1 represents a chlorine, bromine or iodine atom, ???which method comprises reacting ???an organic halide of formula (1):n'(R1X1?n), ???wherein R1 is as defined above and carbon atoms at the α and β positions relative to X1 are sp3 carbon atoms, and X1, n and n' are as defined above, ???with a boron compound of formula (2):m{R2(BX2?2)n'}, ???wherein R2 and n' are as defined above, ???X2 independently represents a hydroxyl group or an alkoxy or aryloxy group, or X22 together form an alkoxy or aryloxy group, and m represents 1 or 2, and m≤n, and the boron atom is bonded with an sp2 carbon atom of R2 group, or a boronic acid trimer anhydride thereof, in the presence of a base and a catalyst comprising a nickel compound and a compound of formula (i): ???wherein R3 represents a substituted or unsubstituted alkyl group, ???R4 represents a hydrogen atom or a substituted or unsubstituted alkyl group, ???1 represents an integer of 1 to 3, and ???p and q each represents an integer of 0 to 2; and a catalyst.
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- Lithium trifluoromethanesulfonate (LiOTf) as a recyclable catalyst for highly efficient acetylation of alcohols and diacetylation of aldehydes under mild and neutral reaction conditions
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A variety of alcohols and aldehydes were reacted with acetic anhydride at room temperature in the presence of a catalytic amount of lithium triflate (LiOTf) to produce the corresponding esters and 1,1-diacetates, respectively, in good to excellent yields under essentially neutral reaction conditions. Sensitive functional groups such as PhCO2-, OMe, and OTBDMS ethers survived intact under the described reaction conditions.
- Karimi, Babak,Maleki, Jafar
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p. 4951 - 4954
(2007/10/03)
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- ZrCl4 as a mild and efficient catalyst for the one-pot conversion of TBS and THP ethers to acetates
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A mild, efficient and chemoselective method has been developed for the direct transformation of tert-butyldimethylsilyl and tetrahydropyranyl protected alcohols into the corresponding acetates with acetic anhydride and zirconium(IV) chloride as the catalyst in acetonitrile, in a one-pot reaction with high yields and short reaction times. This method has been applied to a variety of substrates.
- Reddy, Ch. Sanjeeva,Smitha,Chandrasekhar
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p. 4693 - 4695
(2007/10/03)
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- A fast and practical approach to tetrahydropyranylation and depyranylation of alcohols using indium triflate
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Indium triflate-mediated tetrahydropyranylation of alcohols in dichloromethane and depyranylation of these products in aqueous methanol utilizing the same reagent but different molar ratio is described. In addition, indium triflate-promoted conversion of tetrahydropyran ethers to their corresponding acetates has also been described.
- Mineno, Tomoko
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p. 7975 - 7978
(2007/10/03)
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- Facile acetylation of alcohols, ethers and ketals with catalytic FeCl3 in AcOH
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A simple and efficient protocol for the conversion of alcohols, ethers and ketals to acetates using catalytic FeCl3(5mol%) in AcOH, or AcOH (3eq) in CH2Cl2 in very high yield is reported. A variety of other acids such as CF3CO2H, HCO2H, CH2=CHCO2H, CH3CH2CO2H, CH3(CH2)2CO2H have also been utilised for the acylation of alcohols successfully.
- Sharma,Mahalingam,Nagarajan,Ilangovan,Radhakrishna, Palakodety
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p. 1200 - 1202
(2007/10/03)
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- Effects of Substrate Structure on Lipase-Catalyzed Transesterification of ω-Substituted 1-Alkanols in Organic Solvents.
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Lipase-catalyzed transesterification of ω-phenyl-1-alkanols with vinyl acetate in organic solvents have been investigated.Benzyl alcohol is the most reactive substrate among those studied.It is proposed that a lipase from Pseudomonas cepacia (PCL) has a domain to attract an aromatic moiety of a substrate.
- Nakamura, Kaoru,Kawasaki, Masashi,Ohno, Atsuyoshi
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p. 3053 - 3056
(2007/10/02)
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- Synthesis of long chain ω-aralkylbromides
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1-Iodo-4-acetoxybutane is a useful 4 carbon synthon which reacts selectively with Grignards under copper catalysis. The immediate products are converted to bromides.
- Forth,Smith
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p. 951 - 959
(2007/10/02)
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- Topically active carbonic anhydrase inhibitors. 4. [(hydroxyalkyl)sulfonyl]benzene and [(hydroxyalkyl)sulfonyl]thiophenesulfonamides
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For several decades a tantalizing goal for the treatment of primary open-angle glaucoma has been the development of a topically active carbonic anhydrase inhibitor. Recent results from several research groups indicate that considerable progress has been made toward this objective. In this report, we present the design and synthesis of (hydroxyalkyl)sulfonyl-substituted benzene- and thiophenesulfonamides. These compounds exhibit inhibition of carbonic anhydrase II in the nanomolar range and lower intraocular pressure in the α-chymotrypsinized rabbit model of ocular hypertension after topical instillation.
- Shepard,Graham,Hudcosky,Michelson,Scholz,Schwam,Smith,Sondey,Strohmaier,Smith,Sugrue
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p. 3098 - 3105
(2007/10/02)
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