- Intermolecular Electrophilic Bromoesterification and Bromoetherification of Unactivated Cyclopropanes
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1,3-difunctionalization of cyclopropane is an useful organic transformation. The corresponding 1,3-difunctionalized products are synthetic synthons and building blocks in many organic syntheses. Many existing ring-opening difunctionalization methodologies rely primarily on the use of donor?acceptor cyclopropanes, while the difunctionalization of unactivated cyclopropanes is less exploited. In this research, 1,3-bromoesterification and 1,3-bromoetherification of unactivated cyclopropanes were successfully achieved using N-bromosuccinimide as the brominating agent with high yields and regioselectivity. (Figure presented.).
- Leung, Vincent Ming-Yau,Gieuw, Matthew H.,Ke, Zhihai,Yeung, Ying-Yeung
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supporting information
p. 2039 - 2044
(2020/04/20)
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- Gold-catalyzed ethylene cyclopropanation
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Ethylene can be directly converted into ethyl 1-cyclopropylcarboxylate upon reaction with ethyl diazoacetate (N2CHCO2Et, EDA) in the presence of catalytic amounts of IPrAuCl/NaBArF4 (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazole-2-ylidene; BArF4 = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate).
- Rull, Silvia G.,Olmos, Andrea,Pérez, Pedro J.
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- Synthesis of 3-hydroxyindanones via potassium salt of amino acid catalyzed regioselective intramolecular aldolization of ortho-diacylbenzenes
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First organocatalytic intramolecular aldolization of ortho-diacylbenzenes to construct highly functionalized 3-hydroxyindanones is described. In this transformation a high trans-selectivity is achieved by the use of metal salt of amino acid. This method allows an easy access to the strained spirocyclic 3-hydroxyindanones related to a number of natural product frameworks. Synthesis of a new class of indole skeleton substituted by 3-hydroxyindanones added an extra essence to this new protocol.
- Chanda, Tanmoy,Chowdhury, Sushobhan,Anand, Namrata,Koley, Suvajit,Gupta, Ashutosh,Singh, Maya Shankar
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supporting information
p. 981 - 985
(2015/03/04)
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- Quaternary Ammonium Salt Functionalized Methoxypolyethylene Glycols-Supported Phosphotungstic Acid Catalyst for the Esterification of Carboxylic Acids with Alcohols
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The quaternary ammonium salt functionalized methoxypolyethylene glycols-supported phosphotungstic acid catalyst was prepared and characterized using X-ray diffraction, fourier transform infrared spectroscopy and thermogravimetric analysis. The immobilized phosphotungstic acid catalyst exhibited excellent catalytic activity and selectivity, which was shown to be an efficient heterogeneous catalyst for catalyzing the esterification of carboxylic acids with alcohols under mild conditions. The catalyst could be separated by simple separation and can be used six times without significant losing of catalytic activity and selectivity. Graphical Abstract: [Figure not available: see fulltext.]
- Yang, Zhiwang,Zhao, Lei,Lei, Ziqiang
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p. 585 - 589
(2014/04/03)
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- Cross-coupling of nonactivated alkyl halides with alkynyl grignard reagents: A nickel pincer complex as the catalyst
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In a pinch: The nickel pincer complex 1 catalyzes the cross-coupling of the title compounds with remarkable substrate scope and functional group tolerance. A nickel/alkynyl species was isolated and shown to be catalytically competent. THF=tetrahydrofuran, O-TMEDA=bis[2-(N,N-dimethylaminoethyl)] ether. Copyright
- Vechorkin, Oleg,Godinat, Aurélien,Scopelliti, Rosario,Hu, Xile
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supporting information; experimental part
p. 11777 - 11781
(2012/01/19)
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- Effects of acidity and immiscibility of lactam-based Bronsted-acidic ionic liquids on their catalytic performance for esterification
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Several lactam-based Bronsted-acidic ionic liquids with different acidities were synthesized and applied to the esterification of carboxylic acids with alcohols. High conversion and perfect selectivity were obtained under mild conditions. Among the ionic liquids investigated, those having a methyl sulfonate anion (which has weaker acidity than those with a tetrafluoroborate anion) afforded the highest activity for esterification. The results indicated that the acidity and immiscibility of Bronsted-acidic ionic liquids has a synergistic effect on their esterification performance. Furthermore, after removal of water under vacuum, such ionic liquids could be reused several times without substantial loss of activity.
- Zhou, Hancheng,Yang, Jing,Ye, Linmin,Lin, Haiqiang,Yuan, Youzhu
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experimental part
p. 661 - 665
(2010/08/22)
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- Catalytic ketonisation over oxide catalysts. Part XI*. Cross-ketonisation of esters of aliphatic and aromatic acids
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The cross-ketonisation of a mixture of ethyl acetate and ethyl benzoate under flow conditions has been studied over 20wt%MO2/Al 2O3 (M = Mn, Ce or Zr) catalysts, at 673-723 K. High conversions of aromatic ester up to 98% and moderate yields of acetophenone (2/Al2O3 catalyst was the least selective. In its presence, the yield of styrene (34%) exceeded that of acetophenone (31%). Unexpectedly, pure Al2O3 support exhibited the highest selectivity and moderate activity, at 723 K the yield as high as 51% of acetophenone was noted. The transformations of mixtures of various ethyl alkanoates with ethyl benzoate over alumina have been studied. In the case of straight-chain aliphatic esters, the yields of the corresponding 1-phenyl-1-alkanones were in the range of 41-51%. The presence of a methyl group in the α position of the ester (isobutyrate) reduced the yield of ketone strongly (11%); two methyl groups (pivalate) completely inhibited the reaction. The reactivity of a series of alkyl acetates was also studied in the cross-ketonisation reaction with ethyl benzoate over alumina. It has been found that secondary and tertiary alkyl acetates were slightly more selective than their primary counterparts due to the absence of products of transesterification. For these esters at 723 K the yields of acetophenone were in the range of 64-67%. The cross-ketonisation of a mixture of ethyl acetate with substituted ethyl benzoates led to the corresponding derivatives of acetophenone. It has been found that the position of the substituent in the benzene ring plays a crucial role in the reactivity of the ester and determines the extent of yield of the product. The highest yield of ketone (62%) was observed at 723 K for 3-methylacetophenone. 2-Methylacetophenone was formed with low yields (10%) in the whole range of reaction temperatures, probably due to steric effect in the ortho position. At 698 K the maximum yield of 4-methylacetophenone (27%) was attained. The ketonisation of ethyl acetate with ethyl esters of 4-t-butyl- and 4-chlorobenzoic acids led to moderate yields (24-27%) of 4-t-butyl- and 4-chloroacetophenone, respectively.
- Glinski,Koscik,Jerzak,Synoradzki
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p. 995 - 1001
(2007/10/03)
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- Asymmetric copper complex and cyclopropanation reaction using the same
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There are disclosed asymmetric copper complex comprising, as components, (a) an optically active bisoxazoline compound of formula (1): wherein R1 and R2 are different and each represent a hydrogen atom, an alkyl group, a cycloalkyl group, or a phenyl or aralkyl group which may be substituted, R3 and R4 each represent a hydrogen atom, an alkyl group, a cycloalkyl group, or a phenyl or aralkyl group which may be substituted, or R3 and R4 may be bonded to each other to form a C3-5 cyclic alkylene group, R5 represents a hydrogen atom or a C1-6 alkyl group, or the two R5 groups may be bonded to each other to represent a C3-5 cyclic alkylene group, (b) a monovalent or divalent copper compound, and (c) a strong acid or a Lewis acid or a mixture thereof, and a process for producing an optically active cyclopropanecarboxylate using the same.
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- Chiral copper complex catalyst composition and asymmetric production process using the same
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There is disclosed chiral copper complex catalyst composition, which is obtained by contacting an optically active N-salicylideneaminoalcohol compound of formula (1): with a mono-valent or di-valent copper compound in an inert solvent, wherein R1 and R2 represent an alkyl group and the like, X1 and X2 represent a hydrogen atom, a halogen atom, a nitro group, an alkyl group, an alkoxy group, a cyano group or the like, and the amount of the mono-valent or di-valent copper compound is less than 1 mole per 1 mole of the optically active N-salicylideneaminoalcohol compound of formula (1), and a process for producing an optically active cylopropane-carboxylic acid ester using the same.
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- Processes for the preparation of cyclopropanecarboxylic acid and derivatives thereof
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Disclosed is a process for the preparation of cyclopropanecarboxylic acid by the non-catalytic, oxidation of cyclopropanecarboxaldehyde using molecular oxygen as the oxidant. Also disclosed are processes for the preparation of amides, esters and acid chlorides from cyclopropanecarboxylic acid.
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- Efficient method for removal of a carboxylic acid moiety from sterically crowded cyclopropanedicarboxylic acid derivatives
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A versatile method was developed to the dealkoxycarbonylation of sterically crowded cyclopropanecarboxylic acid derivatives via a nonhydrolytic ester cleavage followed by a Barton-type decarboxylation.
- Hell, Zoltan,Toke, Laszlo
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p. 2127 - 2133
(2007/10/03)
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- Regioselective structural and functional mimicry of peptides. Design of hydrolytically-stable cyclic peptidomimetic inhibitors of HIV-1 protease
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Hydrolytically-stable cyclic mimetics of the tripeptides Leu-Asn-Phe and Phe-Ile-Val were designed and incorporated into peptidic inhibitors, Ac-{Leu-Asn-Phe}-CHOHCH2-Pro-Ile-Val-NH2 and Ac-Leu-Val-Phe-CHOHCH2-{Phe-Ile-Val}-NH2, of HIV-1 protease. Structural mimicry has been established through molecular modeling and X-ray crystallographic studies of inhibitors bound to HIV-1 protease. Cyclic and acyclic inhibitors had similar conformations that were superimposable and formed similar interactions with the enzyme. Functional mimicry was demonstrated by comparable inhibition of the protease by acyclic and cyclic molecules. Further substitution of the residual acyclic Pro-Ile-Val or Leu-Val-Phe inhibitor components, with Pip-NHtBu or Boc-Phe, respectively, gave hydrolytically stable, water-soluble, lipophilic inhibitors of similar potency. The use of cycles to fix the conformations of amino acid sequences in peptides allows regioselective structural mimicry leading to functional mimicry and also permits localized structure-activity optimization in inhibitors of HIV-1 protease. This approach might be usefully applied to inhibitors of other proteins.
- Abbenante,March,Bergman,Hunt,Garnham,Dancer,Martin,Fairlie
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p. 10220 - 10226
(2007/10/03)
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- Process for cyclizing upsilon-chlorocarboxylic acids
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γ-chlorocarboxylic acid methyl or ethyl esters are cyclized to the corresponding cyclopropane carboxylic acid esters by employing the sodium or potassium alcoholate of methanol or ethanol in the presence of the same alcohol at a temperature above the boiling point of the alcohol employed.
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- SYNTHESIS OF E-HOMOALLYLIC ALCOHOLS, γ-HYDROXYKETONES, AND CYCLOPROPYL KETONES FROM 3-DIPHENYLPHOSPHINOYL (Ph2PO) PROPANOLS BY ACYL TRANSFER
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Carboxyl transfer (O*C) on 3-Ph2PO propyl esters (9) gives an intermediate (10) from which the Ph2PO group may be removed by the Horner-Witting reaction or by Ph2PO transfer (C*O) to give the title compounds.
- Wallace, Paul,Warren, Stuart
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p. 5713 - 5716
(2007/10/02)
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- Combating arthropods with perfluorobenzyl 2,2-dimethyl-3-vinyl-cyclopropane carboxylates
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A pentafluorobenzyl 2,2-dimethyl-3-vinylcyclopropane carboxylate of the formula STR1 in which R is hydrogen or halogen, and R1 is optionally substituted phenyl, or R and R1 together constitute an alkylene chain with at least two carbon atoms, which possess arthropodicidal properties.
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- Synthesis of Cyclopropane Derivatives from Electron-deficient Olefins and Dichloromethane via Copper(I) Catalysed Photochemical Addition followed by an Electroreductive Dehalogenation Reaction
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The CuCl-catalysed photochemical reaction of electron-deficient olefins with dichloromethane gave 1,3-dichloro compounds, which then afforded cyclopropane derivatives by electrochemical reduction.
- Mitani, Michiharu,Yamamoto, Yasuo,Koyama, Kikuhiko
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p. 1446 - 1447
(2007/10/02)
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