- Cobalt-Catalyzed Csp3?Csp3Homocoupling
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An efficient and easy method for Csp3?Csp3homocoupling was developed using cobalt bromide as catalyst. A series of functionalized alkyl bromides and alkyl chlorides were coupled in high yields under mild conditions. This reaction seems to involve a radical intermediate. (Figure presented.).
- Cai, Yingxiao,Qian, Xin,Gosmini, Corinne
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supporting information
p. 2427 - 2430
(2016/08/16)
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- A lewis acid-promoted pinner reaction
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Carbonitriles and alcohols react in a Lewis acid-promoted Pinner reaction to carboxylic esters. Best results are obtained with two equivalents of trimethylsilyl triflate as Lewis acid. Good yields are achieved with primary alcohols and aliphatic or benzylic carbonitriles, but the straightforward synthesis of acrylates and benzoates starting with acrylonitrile and benzonitrile, respectively, is similarly possible. Phenols are not acylated under these reaction conditions. The method has been used for the first total synthesis of the natural product monaspilosin. In the reaction of benzyl alcohols variable amounts of amides are formed in a Ritter-type side reaction.
- Pfaff, Dominik,Nemecek, Gregor,Podlech, Joachim
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supporting information
p. 1572 - 1577
(2013/10/22)
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- Lipase-catalysed selective monoacylation of 1,n-diols with vinyl acetate
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A simple enzymatic methodology for the selective monoacetylation of 1,n-diols (n=5,8) using vinyl acetate is reported. Monoacetylation excesses of 81-87% at 74-90% 1,n-diol conversions were obtained in toluene and diisopropyl ether using Thermomyces lanuginosus lipase (TLL) immobilised on polypropylene powder as catalyst.
- Framis, Victoria,Camps, Francisco,Clapés, Pere
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p. 5031 - 5033
(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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- Omega-hydrofluoroalkyl ethers, precursor carboxylic acids and derivatives thereof, and their preparation and application
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Normally liquid, omega-hydrofluoroalkyl ether compounds (and selected mixtures thereof) have a saturated perfluoroaliphatic chain of carbon atoms interrupted by one or more ether oxygen atoms. The compounds can be prepare, e.g. by decarboxylation of the corresponding fluoroalkyl ether carboxylic acids and are useful, e.g., in cleaning and drying applications.
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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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- Solid state acetylation with acetylimidazole: Selective protection of primary alcohols and phenols
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Primary alcohols and phenols have been acetylated with acetylimidazole by the solid state reaction, grinding both substrates with a pestle in a mortar.
- Hagiwara, Hisahiro,Morohashi, Kimie,Suzuki, Toshio,Ando, Masayoshi,Yamamoto, Isao,Kato, Michiharu
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p. 2001 - 2006
(2007/10/03)
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- A remarkably simple process for monoprotecting diols
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Lipase from pig pancreas (PPL) has been shown to catalyse selectively the hydrolysis of alkane-1,n-diol bis-acetates into the corresponding monoacetate.
- Houille, Olivier,Schmittberger, Thierry,Uguen, Daniel
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p. 625 - 628
(2007/10/02)
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- Convenient Selective Monoacylation of 1,n-Diols Catalyzed by Ion-Exchange Resins
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Several 1,n-diols, ranging from 1,2-ethanediol to 1,16-hexadecanediol, were selectively monoacylated by transestrification in ester/octane solvent mixtures catalyzed by strongly acidic ion-exchange resisns.This method of selective esterification is quite simple and practical.The selectivity for monoester formation and initial rates of monoester formation depended on the ester/octane ratio of the solvents.The reasons for the selectivity are as follows: (1) The sulfonic acid-type ion-exchange resins usually contain 50-80percent water, and a strongly acidic aqueous layer is formed on the surface of the resins. (2) A partition equilibrium between the aqueous layer and the aprotic ester/octane layer is setup, and diols have higher partition coefficients than the product monoesters. (3) Acylation of the alcohols occurs in the aqueous layer and/or at the interface between the aqueous and the nonaqueous liquid layer. (4) The formed monoesters move away from the aqueous layer into the aprotic layer.
- Nischiguchi, Takeshi,Fujisaki, Shizuo,Ishii, Yasuhiro,Yano, Yoshihiro,Nishida, Akiko
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p. 1191 - 1195
(2007/10/02)
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- A One-step and Chemoselective Conversion of Silyl-protected Alcohols into the Corresponding Acetates
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A reagent system of acetyl bromide combined with a catalytic amount of tin(II) bromide cleaves readily trialkylsilyl ethers to give the corresponding acetates in high yields under very mild conditions.
- Oriyama, Takeshi,Oda, Mihoko,Gono, Junko,Koga, Gen
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p. 2027 - 2030
(2007/10/02)
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- Highly Selective Monoacylation of Symmetric Diols Catalyzed by Metal Sulfates Supported on Silica Gel
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Several 1,α-diols, ranging from 1,2-ethanediol to 1,16-hexadecanediol, were monoacylated with high selectivity by reaction with esters in the presence of metal sulfates or hydrogen sulfates, like Ce(SO4)2 and NaHSO4, supported on silica gel.Symmetrical secondary diols were also selectively monoformylated, by reaction with ethyl formate.This method of selective esterification is simple and practical.The yield of monoester depends upon both the composition and the volume of the solvent (an ester/alkane mixture).Unsupported NaHSO4 also catalyzed monoacylation, but the selectivity was less than in monoacylations catalyzed by the supported reagent.The selectivity can be explained by the following reasons: (1) monoacylated products are formed selectively because the diol, but not the monoester, is preferentially adsorbed on the surface of the catalysts, where esterification then occurs, and (2) thin diol layers are formed on the surface of the catalysts due to limited solubility of the diols in the solvent.
- Nishiguchi, Takeshi,Kawamine, Katsumi,Ohtsuka, Tomoko
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p. 312 - 316
(2007/10/02)
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