- Palladium-Catalyzed Three-Component Coupling Reaction of Allyl Carboxylates, Norbornenes and Diboronates Involving Sequential Olefins Insertion and Borylation Reaction
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An efficient Pd-catalyzed three-component coupling reaction of allyl carboxylates, norbornenes and diboronates is described, which allows efficient assembly of C(sp3)—C(sp3) and C(sp3)—B bonds in a single process. Moreover, this approach shows advantages of good chemo- and regioselectivity, as well as good substrates suitability.
- Li, Zun,Zheng, Jia,Li, Chunsheng,Wu, Wanqing,Jiang, Huanfeng
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p. 140 - 147
(2019/01/21)
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- Cinnamyl alcohol fatty acid ester derivative and application and preparation method thereof
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The invention relates to a derivative and an application and a preparation method thereof, in particular to a cinnamyl alcohol fatty acid ester derivative and an application and a preparation method thereof. As application of a percutaneous absorption penetration enhancer, a percutaneous administration preparation is prepared, so that the percutaneous absorption of a drug is improved, and the cumulative penetration amount of the drug is increased. The cinnamyl alcohol fatty acid ester derivative is prepared into fatty acyl chloride, and the fatty acyl chloride reacts with cinnamyl alcohol to obtain the cinnamyl alcohol fatty acid ester derivative. The compound can be applied to the percutaneous administration preparation to enhance the drug permeability, can further be used as perfume to cover up the bad smell of the preparation, and has wide potential application prospects.
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Paragraph 0040; 0041
(2019/05/08)
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- Efficient Enzymatic Preparation of Flavor Esters in Water
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A straightforward biocatalytic method for the enzymatic preparation of different flavor esters starting from primary alcohols (e.g., isoamyl, n-hexyl, geranyl, cinnamyl, 2-phenethyl, and benzyl alcohols) and naturally available ethyl esters (e.g., formate, acetate, propionate, and butyrate) was developed. The biotransformations are catalyzed by an acyltransferase from Mycobacterium smegmatis (MsAcT) and proceeded with excellent yields (80-97%) and short reaction times (30-120 min), even when high substrate concentrations (up to 0.5 M) were used. This enzymatic strategy represents an efficient alternative to the application of lipases in organic solvents and a significant improvement compared with already known methods in terms of reduced use of organic solvents, paving the way to sustainable and efficient preparation of natural flavoring agents.
- Perdomo, Igor Chiarelli,Gianolio, Stefania,Pinto, Andrea,Romano, Diego,Contente, Martina Letizia,Paradisi, Francesca,Molinari, Francesco
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p. 6517 - 6522
(2019/06/20)
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- Synthesis of α-(Pentafluorosulfanyl)- and α-(Trifluoromethyl)-Substituted Carboxylic Acid Derivatives by Ireland-Claisen Rearrangement
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Earlier studies have shown that [3,3]-sigmatropic rearrangements of allyl esters are useful for the construction of fluorine-containing carboxylic acid derivatives. This paper describes the synthesis of 3-aryl-pent-4-enoic acid derivatives bearing either a pentafluorosulfanyl (SF5) or a trifluoromethyl (CF3) substituent in the 2-position by treatment of corresponding SF5- or CF3-acetates of p-substituted cinnamyl alcohols with triethylamine followed by trimethylsilyl triflate (TMSOTf). This Ireland-Claisen rearrangement delivered approximate 1:1 mixtures of syn/anti diastereoisomers due to tiny differences (3N) led to oligomerization of the cinnamyl SF5- and CF3-acetates. Treatment of the corresponding regioisomeric 1-phenyl-prop-2-en-1-yl acetates under the latter conditions resulted in [1,3]-sigmatropic rearrangement and subsequent oligomerization of the intermediately formed cinnamyl esters. When Et3N was added first followed by TMSOTf, no further reaction of the formed ester was detected.
- Dreier, Anna-Lena,Beutel, Bernd,Mück-Lichtenfeld, Christian,Matsnev, Andrej V.,Thrasher, Joseph S.,Haufe, Günter
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p. 1638 - 1648
(2017/02/10)
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- An examination of the scope and stereochemistry of the Ireland-Claisen rearrangement of boron ketene acetals
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The Ireland-Claisen rearrangement of boron ketene acetals is described. The boron ketene acetal intermediates are formed through a soft enolization that obviates the use of strong bases and the intermediacy of alkali metal enolates. Yields and diastereoselectivities of these rearrangements are very sensitive to the choice of boron reagent, even among those that have been shown to effect quantitative formation of boron ketene acetals from esters. The rearrangement occurs at room temperature for all substrates with generally high levels of stereoselectivity. In contrast to previous reports using boron triflates, the use of a commercially available boron iodide reagent allows for a wider substrate scope that extends to propionates and arylacetates, as well as the previously described α-oxygenated esters. This work also provides insight into the dynamic nature of boron ketene acetals and the ramifications of this behavior for reactions in which they are intermediates. Borane down: Boron enolates of allylic esters are efficiently generated at -78 °C using cHx2BI (dicyclohexyliodoborane)·Et3N. These rearrange smoothly on being warmed to room temperature to give generally high diastereoselectivity in forming γ,δ-unsaturated acids (see scheme). The rearrangements provide a key insight into the dynamic nature of boron ketene acetals.
- Seizert, Curtis A.,Ferreira, Eric M.
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supporting information
p. 4460 - 4468
(2014/05/06)
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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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- Indium-mediated Reformatsky-Claisen rearrangement
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A new variant of the Reformatsky-Claisen rearrangement is described. The reaction of substituted allyl α-bromoacetates with indium and indium(III) chloride under ultrasonication provides a general entry into the functionalized synthon.
- Ishihara, Jun,Watanabe, Yuki,Koyama, Noriko,Nishino, Yukihiro,Takahashi, Keisuke,Hatakeyama, Susumi
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p. 3659 - 3667
(2011/06/21)
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- 5H-3-oxa-Octafluoropentanesulfonyl fluoride: a novel and efficient condensing agent for esterification, amidation and anhydridization
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The use of 5H-3-oxa-octafluoropentanesulfonyl fluoride (HCF2CF2OCF2CF2SO2F) as a novel and efficient condensing reagent for esterification of carboxylic acids with alcohols and amidation of carboxylic acids with amines in the presence of 1,3-diazabicyclo[5.4.0]-undec-7-ene (DBU) is reported. HCF2CF2OCF2CF2SO2F cannot serve as a condensing agent for anhydridization of carboxylic acids, however, HCF2CF2OCF2CF2SO2F/(CH3)3SiCN system can mediate anhydridization of some aromatic carboxylic acids.
- Yan, Zhaohua,Tian, Weisheng,Zeng, Fanrong,Dai, Yanfeng
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experimental part
p. 2727 - 2729
(2009/09/06)
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- N, O-ligand accelerated zinc-catalyzed transesterification of alcohols with vinyl esters
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N-Phenyldiethanolamine (1f) is an efficient ligand for zinc-catalyzed transesterification of alcohols with vinyl acetate (R3 = Me) at room temperature. In the case of using other vinyl esters (R3 = Et, n-Pr, Ph), the corresponding products were easily obtained in the presence of pyridine-type ligand 2 instead of aminoalcohol 1f.
- Mino, Takashi,Hasegawa, Tae,Shirae, Yoshiaki,Sakamoto, Masami,Fujita, Tsutomu
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p. 4389 - 4396
(2008/02/13)
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- Synthesis under reversible conditions of cyclic porphyrin dimers using palladium-catalysed allyl transesterification
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Cyclic zinc-porphyrin dimers have been synthesised using reversible π-allyl palladium chemistry in the presence of bidentate pyridyl ligand templates.
- Kaiser,Sanders
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p. 1763 - 1764
(2007/10/03)
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- Catalytic esterification of alcohols, carboxylic acids and transesterification reactions with cerium(IV) triflate
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Esterification reactions of alcohols with acetic, chloroacetic, trifluoroacetic, propionic, stearic, and benzoic acids were catalyzed with Ce(OTf)4 in a solvent or under solvent-free conditions with high yields. The formylation and acetylation of primary and secondary alcohols were also easily achieved in ethyl formate and ethyl acetate. A high retention of the configuration was observed in the acetylation and formylation of (-)-menthol.
- Iranpoor, Nasser,Shekarriz, Marzieh
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p. 455 - 458
(2007/10/03)
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- Generation of esters from carboxylic acids using Appel's salt (4,5-dichloro-1,2,3-dithiazolium chloride)
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Esters can be generated directly in good yields under mild conditions from the corresponding carboxylic acid and alcohol using Appel's salt (4,5-dichloro-1,2,3-dithiazolium chloride) and 2,6-lutidine.
- Folmer,Weinreb
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p. 2737 - 2740
(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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- Ketal Claisen Rearrangements of Simple Aliphatic Ketals
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The ketal Claisen rearrangement has been studied with eight simple unsymmetrical ketals in order to establish the regioselectivity associated with the transformation.Three different allylic alkohols were examined.Carbon-carbon bond formation on the more highly substituted branch of the parent ketone generally predominated over substitution on the less highly substituted branch.However, additional substituents on the α or β carbons of the ketal lower the selectivity substantially.Extensive β substitution can completely reverse the normal selectivity.The rection is relatively insensitive to the concentration of the weak acid catalyst.The yields range between 27 and 84 percent, and the products have been characterized.A model that accounts for the observations is also described.
- Daub, G. William,McCoy, Mark A.,Sanchez, Michael G.,Carter, James S.
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p. 3876 - 3883
(2007/10/02)
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- Sodium Borohydride-Carboxylic Acid Systems - A new Method of Acylation of Alcohols, Phenols and Thiophenols
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A new method of acylation of alcohols, phenols and thiophenols in sodium borohydride-carboxylic acid system is described.A plausible mechanism of this acylation through tetraacyloxyborate derivative has been postulated.
- Prashad, Mahavir,Jigajinni, Veerappa B.
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p. 822 - 823
(2007/10/02)
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