- Photoinduced Diverse Reactivity of Diazo Compounds with Nitrosoarenes
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A diverse reactivity of diazo compounds with nitrosoarene in an oxygen-transfer process and a formal [2 + 2] cycloaddition is reported. Nitosoarene has been exploited as a mild oxygen source to oxidize an in situ generated carbene intermediate under visible-light irradiation. UV-light-mediated in situ generated ketenes react with nitosoarenes to deliver oxazetidine derivatives. These operationally simple processes exemplify a transition-metal-free and catalyst-free protocol to give structurally diverse α-ketoesters or oxazetidines.
- Roy, Sourav,Kumar, Gourav,Chatterjee, Indranil
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supporting information
p. 6709 - 6713
(2021/09/08)
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- Preparation of Organic Nitrates from Aryldiazoacetates and Fe(NO3)3·9H2O
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A thermal protocol is reported for the formal insertion of nitric acid into aryldiazoacetates using Fe(NO3)3·9H2O. This strategy is mild and high yielding and allows the preparation of a large variety of members of an unprecedented family of organic nitrates. The nitrate group can be also readily transformed into other functional groups and heterocyclic moieties and can possibly allow new biological explorations of untapped potential associated with their NO-releasing ability.
- Thurow, Samuel,Fernandes, Alessandra A. G.,Quevedo-Acosta, Yovanny,De Oliveira, Matheus F.,De Oliveira, Marcelo G.,Jurberg, Igor D.
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supporting information
p. 6909 - 6913
(2019/09/12)
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- LED lighting as a simple, inexpensive, and sustainable alternative for Wolff rearrangements
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The Wolff rearrangement is one of the best methods for chain homologation. However, it still suffers from many drawbacks with respect to its practical execution in the laboratory. We wish to demonstrate the use of commercial LED lamps as a sustainable alternative for the classic experimental protocols typically used for Wolff rearrangements. This journal is
- Bernardim, Barbara,Hardman-Baldwin, Andrea M.,Burtoloso, Antonio C. B.
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p. 13311 - 13314
(2015/02/19)
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- SO3H and NH2+ functional carbon-based solid acid catalyzed transesterification and biodiesel production
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A SO3H and NH2+ functional carbon-based solid acid was used as a highly active heterogeneous catalyst for the transesterification of various carboxylic methyl esters with alcohols under mild conditions. It also showed high catalytic performance for transesterification of triolein with methanol or isopropanol. Furthermore, it was able to catalyze simultaneous esterification and transesterification of rice oil and butter respectively, the yields of biodiesel obtained were up to 94%, and the catalyst could be easily recovered and reused more than ten times without loss of activity, which indicated the carbon-based solid acid was a potential catalyst for the biodiesel industry.
- Cai, Liangzhen,Meng, Decai,Zhan, Shaoqi,Yang, Xiaoxia,Liu, Taoping,Pu, Huiming,Tao, Xiaochun
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p. 72146 - 72149
(2015/09/08)
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- Copper(II)-acid catalyzed cyclopropanation of 1,3-dienamides by electrophilic activation of α-aryl diazoesters
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Copper(II)-acid catalyzed cyclopropanation of electron-rich alkenes, such as 1,3-dienamides, with α-aryl diazoesters are described. The reaction could be performed without rare metal catalysts, excess substrate, or the need for the slow addition of the diazoesters.
- Tayama, Eiji,Horikawa, Kouki,Iwamoto, Hajime,Hasegawa, Eietsu
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supporting information
p. 3041 - 3044
(2014/05/20)
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- The carbon material functionalized with NH2+ and SO3H groups catalyzed esterification with high activity and selectivity
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A novel carbon-based solid acid was conveniently prepared by heating a mixture of d-glucose, p-toluenesulfonic acid and diphenylammonium tosylate. Its structure was measured by XRD, FT-IR, XPS, 13C MAS NMR and EA to illustrate that the carbon material has been functionalized with NH2+ and SO3H groups and has a strong "hydrophobic effect". It can be used to catalyze the esterification reaction of carboxylic acids with equimolar amounts of sterically demanding and acid-sensitive alcohols with high reactivity (yield up to 90%) and selectivity (up to 95%) in heptane at 80 °C. It could be easily recovered and reused more than ten times without loss of activity.
- Zhan, Shaoqi,Tao, Xiaochun,Cai, Liangzhen,Liu, Xiaohui,Liu, Taoping
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supporting information
p. 4649 - 4653
(2015/02/19)
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- Use of diethoxymethane as a solvent for phase-transfer esterification of carboxylic acids
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The esterification of carboxylic acids with selected primary alkyl halides in diethoxymethane (DEM) utilizing solid-liquid phase-transfer catalysis has been studied. The use of DEM as the solvent simplifies the process in that a single solvent can be used for both reaction and workup.
- Coleman, M. Todd
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scheme or table
p. 1911 - 1913
(2012/06/04)
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- Palladium-catalyzed divergent reactions of α-diazocarbonyl compounds with allylic esters: Construction of quaternary carbon centers
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Take two: α-Diazocarbonyl compounds display a diverse pattern of reactivity upon palladium-catalyzed reaction with esters. Esters bearing an alkynyl group on the carbonyl carbon atom lead to two different C-C bonds at the same carbon atom in a single operation through decarboxylation and migratory insertion, whereas aromatic and benzylic acid derivatives afford aromatic and benzylic esters bearing an O-substituted quaternary carbon center. Copyright
- Chen, Zi-Sheng,Duan, Xin-Hua,Zhou, Ping-Xin,Ali, Shaukat,Luo, Jian-Yi,Liang, Yong-Min
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supporting information; experimental part
p. 1370 - 1374
(2012/03/27)
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- Protic acid immobilized on solid support as an extremely efficient recyclable catalyst system for a direct and atom economical esterification of carboxylic acids with alcohols
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(Chemical Equation Presented) A convenient and clean procedure of esterification is reported by direct condensation of equimolar amounts of carboxylic acids with alcohols catalyzed by an easy to prepare catalyst system of perchloric acid immobilized on silica gel (HClO4-SiO2). The direct condensation of aryl, heteroaryl, styryl, aryl alkyl, alkyl, cycloalkyl, and long-chain aliphatic carboxylic acids with primary/secondary alkyl/cycloalkyl, allyl, propargyl, and long-chain aliphatic alcohols has been achieved to afford the corresponding esters in excellent yields. Chiral alcohol and N-t-Boc protected chiral amino acid also resulted in ester formation with the representative carboxylic acid or alcohol without competitive N-t-Boc deprotection and detrimental effect on the optical purity of the product demonstrating the mildness and chemoselectivity of the procedure. The esters of long-chain (>C10) acids and alcohols are obtained in high yields. The catalyst is recovered and recycled without significant loss of activity. The industrial application of the esterification process is demonstrated by the synthesis of prodrugs of ibuprofen and a few commercial flavoring agents. Other protic acids such as H2SO4, HBr, TfOH, HBF4, and TFA that were adsorbed on silica gel were less effective compared to HClO4-SiO2 following the order HClO4-SiO 2 ? H2SO4-SiO2 > HBr-SiO 2 > TfOH-SiO2 ? HBF4-SiO2 ≈ TFA-SiO2. When HClO4 was immobilized on other solid supports the catalytic efficiency followed the order HClO4-SiO 2 > HClO4-K10 > HClO4-Al 2O3 (neutral) > HClO4-Al2O 3 (acidic) > HClO4-Al2O3 (basic).
- Chakraborti, Asit K.,Singh, Bavneet,Chankeshwara, Sunay V.,Patel, Alpesh R.
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supporting information; experimental part
p. 5967 - 5974
(2009/12/24)
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- Studies on the structure-activity relationship of bicifadine analogs as monoamine transporter inhibitors
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Compounds with various activities and selectivities were discovered through structure-activity relationship studies of bicifadine analogs as monoamine transporter inhibitors. The norepinephrine-selective 2-thienyl compound S-6j was efficacious in a rodent
- Zhang, Mingzhu,Jovic, Florence,Vickers, Troy,Dyck, Brian,Tamiya, Junko,Grey, Jonathan,Tran, Joe A.,Fleck, Beth A.,Pick, Rebecca,Foster, Alan C.,Chen, Chen
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scheme or table
p. 3682 - 3686
(2009/04/06)
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- Scandium triflate catalyzed transesterification of carboxylic esters
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The direct transesterification of carboxylic esters is efficiently catalyzed with Sc(OTf)3 (10 mol%) in boiling alcoholic solvent. Methyl, ethyl, isopropyl, and allyl esters were prepared from a broad range of different substrates in high yields. The application of microwave irradiation led to significantly reduced reaction times. Georg Thieme Verlag Stuttgart.
- Remme, Nicole,Koschek, Katharina,Schneider, Christoph
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p. 491 - 493
(2007/12/27)
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- Efficient photolytic esterification of carboxylic acids with alcohols in perhalogenated methane
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Condensation of carboxylic acids and alcohols to give esters was accomplished with selectivity under photolytic conditions in 66-99% yields by use of CCl4 or BrCCl3 at room temperature.
- Hwu, Jih Ru,Hsu, Chuan-Yi,Jain, Moti L.
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p. 5151 - 5154
(2007/10/03)
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- A New Enantioselective Synthesis of Milnacipran and an Analogue by Catalytic Asymmetric Cyclopropanation
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Milnacipran and analogues are conveniently prepared by a short sequence of steps from phenylacetic acid, the key step being highly enantio-selective catalytic asymmetric cyclopropanation.
- Doyle, Michael P.,Hu, Wenhao
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p. 299 - 302
(2007/10/03)
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- Dirhodium(II) tetrakis[methyl 2-oxaazetidine-4-carboxylate]: A chiral dirhodium(II) carboxamidate of exceptional reactivity and selectivity
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A new chiral azetidinone-carboxylate ligand for dirhodium(II) catalysts enhances reactivity toward diazo decomposition and selectivity toward cyclopropanation enabling diazomalonates, vinyldiazoacetates, and aryldiazoacetates to be effectively used with a dirhodium(II) carboxamidate catalyst.
- Doyle, Michael P.,Davies, Simon B.,Hu, Wenhao
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p. 1145 - 1147
(2007/10/03)
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- An improved synthesis of a polymer-supported distannane and its application to radical formation
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A polymer-supported distannane 1 was prepared by treatment of tin halide resin with lithium naphthalenide or sodium naphthalenide in THF. The content of the polymers 1 was determined to be 0.95 to 1.13 mmol/g tin as ditin. The polymer-supported distannane reagent was successfully applied to radical cyclizations of acyclic α-haloesters to yield γ-butyrolactones.
- Junggebauer, Joerg,Neumann, Wilhelm P.
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p. 1301 - 1310
(2007/10/03)
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- Dependence of the reactivities of titanium enolates on how they are generated: Diastereoselective coupling of phenylacetic acid esters using titanium tetrachloride
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Oxidative coupling of phenylacetic acid esters was easily achieved by treating the esters with TiCl4 and then adding Et3N to the resulting solution. The products consisted of dl- and meso-2,3-diphenylsuccinic acid esters with the Claisen condensation product, and the ratio of these products depended on the reaction conditions. Reaction conditions suitable for high dl selectivity were determined, and a dimer of titanium enolate was postulated as an intermediate responsible for the high dl selectivity. The selectivities were compared with those in known oxidative couplings in which titanium enolate intermediates are prepared through lithium enolates and silyl enol ethers. The results suggest that the reactivities of titanium enolates intermediates depend on how they are generated.
- Matsumura, Yoshihiro,Nishimura, Maiko,Hiu, Hiroyuki,Watanabe, Mitsuaki,Kise, Naoki
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p. 2809 - 2812
(2007/10/03)
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- THE SYNTHESIS, CHARACTERISATION AND REACTIVITY OF SOME LEAD(IV) CARBOXYLATES
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A detailed examination of the preparation, characterisation and reactivity of a range of lead(IV) carboxylates is reported.The replacement of the acetate ligands of lead(IV) tetraacetate by other carboxylates gives the lead(IV) tetracarboxylates 1-16, which have usually been found to be more stable than lead tetraacetate with respect to hydrolysis.These compounds react with allyltributylstannane to give high yields of the corresponding allyl esters 20-34 under mild conditions.
- Buston, Jonathan E. H.,Coop, Andrew,Keady, Richard,Moloney, Mark G.,Thompson, Russell M.
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p. 1101 - 1116
(2007/10/02)
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- Mild, one-pot conversion of carboxylic acids into esters using phase transfer catalysis
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One-pot conversion of carboxylic acids into esters under the influence of phase transfer catalysis is reported.The method is shown to work satisfactorily for optically active acids having epimerisable α-hydrogen.
- Puntambekar, Hemalata M,Naik, D G,Kapadi, A H
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p. 793 - 794
(2007/10/02)
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- Transesterifications with 1,8-Diazabicycloundec-7-ene/Lithium Bromide (DBU/LiBr) - Also Applicable to Cleavage of Peptides from Resins in Merrifield Syntheses
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A mixture of the amidine base 1,8-diazabicycloundec-7-ene (DBU) and LiBr (preferably 0.5 and 5 equiv., resp.) turns out to be a highly efficient catalyst (at 0-25 deg C) for saponifications (in THF/H2O) and transesterifications (in ROH).The scope and limitations of the method are determined using ca. two dozens of different ester/alcohol combinations (Schemes 2 and 3).The investigation is focused on peptides as substrates.Under carefully controlled conditions, no epimerization occurs with N-Boc- and N-Z-protected peptide esters, when methyl, ethyl, isopropyl, or allyl esters are the products, as shown for peptides containing up to six amino acids, with Ala, Leu, MeLeu, Asp(OEt), or Tyr at the C-terminus (Scheme 3 and Tables 1 and 2).Hydrolytic and transesterifying detachments of Boc-Leu-Ala-Gly-Val-OR and Boc-Leu-Ala-Gly-Phe-OR (R = H, Me) from PAM and Wang resins (1-8 h at 0-25 deg C, 2 equiv. of DBU, 5 equiv. of LiBr) can be achieved by this method without epimerization of the C-terminal stereogenic center; a comparison with other methods (HF, Ti(OR)4) is given (Schemes 4 and 5).Possible protecting-group strategies involving the DBU/LiBr method are discussed (Table 3).Extensive experimental details are given.
- Seebach, Dieter,Thaler, Adrian,Blaser, Denis,Ko, Soo Y.
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p. 1102 - 1118
(2007/10/02)
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- Transesterification of methyl arylacetates wtih lithium alkoxides
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A series of methyl arylacetates were transesterified in excellent yields using lithium alkoxides derived from primary, secondary, and tertiary aliphatic alcohols, benzyl alcohols, and allyl alcohol.
- Bhawal,Khanapure,Biehl
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p. 112 - 114
(2007/10/02)
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- THE NITROGENATED ALLYLIC SYSTEM AS AN INTRAMOLECULAR NUCLEOPHILE: A NEW ROUTE TO PYRAZOLES
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A new route to pyrazoles via the cyclization of N-allyl-N-nitrosoamides is described.
- Momose, Takefumi,Toyooka, Naoki,Ikuta, Takashi,Yanagino, Hironobu
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p. 789 - 793
(2007/10/02)
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- S,S'-Bis(1-phenyl-1H-tetrazol-5-yl) Dithiocarbonate: A New Esterification Reagent
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S,S'-Bis(1-phenyl-1H-tetrazol-5-yl) dithiocarbonate is a useful reagent for the esterification of carboxylic acids with alcohols, including lactonization.The reagent is conveniently prepared in good yield from 1-phenyl-5-thioxo-4,5-dihydro-1H-tetrazole and trichloromethyl chloroformate (trichloromethyl carbonochloridate) in ethyl acetate in the presence of triethylamine.Its structure was confirmed by (13)C-NMR spectrometry and single-crystal X-ray analysis.
- Takeda, Kazuyoshi,Tsuboyama, Kanoko,Takayanagi, Hiroaki,Ogura, Haruo
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p. 560 - 562
(2007/10/02)
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