- Triethylamine-promoted elimination from (R,R)-PhCHORCHClCO2Me (R = MeCO, PhCO, 4-MeC6H4, 4-MeOC6H4, MeSO2 and 4-MeC6H4SO2) in various solvents
-
The rates and stereochemistry of elimination from a number of (R,R)- PhCHORCHClCO2Me (R = MeCO, PhCO, 4-MeC6H4, 4-MeOC6H4, MeSO2 and 4- MeC6H4SO2) with trie
- Montani, Rosana S.,Gil, Elisabet,Cabaleiro, Mercedes C.
-
-
Read Online
- One-Step Preparation of α-Chloro-α,β-unsaturated Carbonyl Compounds by the Reaction of Silyl Enol Ethers with TiCl4-LiAlH4-CCl4
-
Reaction of silyl enol ethers in a system composed of TiCl4, LiAlH4, and CCl4, which generates dichlorocarbene, produced α-chloro-α,β-unsaturated carbonyl compounds in an one-step process.
- Mitani, Michiharu,Kobayashi, Yoshinori
-
-
Read Online
- Visible light-mediated metal-free double bond deuteration of substituted phenylalkenes
-
Various bromophenylalkenes were reductively photodebrominated by using 1,3-dimethyl-2-phenyl-1H-benzo-[d]imidazoline (DMBI) and 9,10-dicyanoanthracene. With deuterated DMBI analogs (the most effective was DMBI-d11), satisfactory to excellent isotopic yields were obtained. DMBI-d11 could also be regenerated from the reaction mixtures with a recovery rate of up to 50%. The combination of the photodebromination reaction with conventional methods for bromoalkene synthesis enables sequential monodeuteration of a double bond without the necessity of a metal catalyst. This journal is
- Iakovenko, Roman,Hlavá?, Jan
-
supporting information
p. 440 - 446
(2021/01/28)
-
- Titanium mediated olefination of aldehydes with α-haloacetates: An exceptionally stereoselective and general approach to (Z)-α-haloacrylates
-
An exceptionally stereoselective and general synthesis of (Z)-α-haloacrylates, ready to undergo various synthetic transformations, has been demonstrated from α-haloacetates and aldehydes in a one-pot manner via the titanium-enolate based asymmetric aldol
- Augustine, John Kallikat,Bombrun, Agnes,Venkatachaliah, Srinivasa,Jothi, Anandh
-
p. 8065 - 8072
(2013/12/04)
-
- Ru-catalyzed highly chemo- and enantioselective hydrogenation of γ-halo-γ,δ-unsaturated-β-keto esters under neutral conditions
-
Finely-tuned ruthenium-catalyzed highly chemoselective and enantioselective hydrogenation of γ-halo-γ,δ-unsaturated-β-keto esters at the carbonyl group was achieved under neutral reaction conditions (ee up to 97%). Both olefin and alkenyl halogen moieties, which are labile under hydrogenation conditions, remained untouched during the reaction.
- Ma, Xin,Li, Wanfang,Li, Xiaoming,Tao, Xiaoming,Fan, Weizheng,Xie, Xiaomin,Ayad, Tahar,Ratovelomanana-Vidal, Virginie,Zhang, Zhaoguo
-
supporting information; experimental part
p. 5352 - 5354
(2012/06/30)
-
- A substrate-driven approach to determine reactivities of α,β-unsaturated carboxylic esters towards asymmetric bioreduction
-
The degree of C=C bond activation in the asymmetric bioreduction of α,β-unsaturated carboxylic esters by ene-reductases was studied, and general recommendations to render these "borderline-substrates" more reactive towards enzymatic reduction are proposed. The concept of "supported substrate activation" was developed. In general, an additional α-halogenated substituent proved to be beneficial for enzymatic activity, whereas β-alkyl or β-aryl substituents were detrimental for the reactivity of nonhalogenated substrates, and α-cyano groups showed little effect. The alcohol moiety of the ester functionality was found to have a strong influence on the reaction rate. Overall, activities were determined by both steric and electronic effects. Biotransformation: The asymmetric bioreduction of α,β-unsaturated carboxylic esters by ene-reductases could be tuned by varying the degree of C=C bond activation (see scheme). An additional α-halogenated substituent proved to be beneficial for enzymatic activity, whereas β-alkyl or β-aryl substituents were detrimental for the reactivity of nonhalogenated substrates. Copyright
- Tasnádi, Gábor,Winkler, Christoph K.,Clay, Dorina,Sultana, Nargis,Fabian, Walter M. F.,Hall, Mélanie,Ditrich, Klaus,Faber, Kurt
-
supporting information; experimental part
p. 10362 - 10367
(2012/10/08)
-
- Biocatalyzed enantioselective reduction of activated C=C bonds: Synthesis of enantiomerically enriched α-halo-β-arylpropionic acids
-
The enantioselective biocatalyzed reduction of the C=C bond of some (Z)-methyl α-halo-β-arylacrylates was investigated. The reaction was performed by baker's yeast fermentation and Old Yellow Enzymes 1-3 mediated biotransformations. The final products wer
- Brenna, Elisabetta,Gatti, Francesco G.,Manfredi, Alessia,Monti, Daniela,Parmeggiani, Fabio
-
experimental part
p. 4015 - 4022
(2011/09/15)
-
- Pd0-Catalyzed carbonylation of 1,1-dichloro-1-alkenes, a new selective access to Z-α-chloroacrylates
-
A novel and fully chemo- and stereoselective three component strategy leading to Z-α-chloroacrylates by a Pd0-catalyzed reaction of CO (1 atm) with 1,1-dichloro-1-alkenes and various alcohols is disclosed. This catalytic approach compares favourably with the Wittig type strategies as α-chloroacrylates of pure Z configuration are obtained in high yield. The Royal Society of Chemistry.
- Arthuis, Martin,Lecup, Anne,Roulland, Emmanuel
-
supporting information; experimental part
p. 7810 - 7812
(2010/11/18)
-
- One-pot synthesis of (E)-a-chloro-a,β-unsaturated esters
-
Chlorination of a phosphonate anion derived in situ from methyl bis(2,2,2-trifluoroethoxylphosphonoacetate 2 followed by the addition of aldehydes constitutes a stereoselective single flask procedure for the preparation of E-configured a-chloro-a,β-unsatu
- Karama, Usama
-
experimental part
p. 405 - 406
(2009/12/25)
-
- N-heterocyclic carbenes of indazole: Ring enlargement reactions by α-halo ketones and dehalogenations of vicinal dihalides
-
On decarboxylation, 1,2-dimethylindazolium-3-carboxylate forms the N-heterocyclic carbene, 1,2-dimethylindazol-3-ylidene, which deprotonates α-halo ketones. The resulting indazolium salt and the corresponding enolate form 1:1 adducts which undergo a ring enlargement to cinnolines. Reaction with 2-bromo-2,3-dihydro-1H-inden-1-one gives a 4- hydroxyspiro[cinnoline-3,2′-inden]-1′-one by ring enlargement reaction (X-ray crystal structure analysis). Vicinal dibromides undergo debromination under these conditions to give alkenes, and substrates with 1,2-dibromoethene partial structure give acetylenes. As 3-bromoindazole is found as the second product of this reaction, an E1cb mechanism, initiated by Br+ abstraction by the N-heterocyclic carbene of indazole, is suggested. Georg Thieme Verlag Stuttgart.
- Schmidt, Andreas,Snovydovych, Bohdan,Gjikaj, Mimoza
-
experimental part
p. 2798 - 2804
(2009/04/05)
-
- A novel and convenient protocol for synthesis of a-haloacrylates
-
A novel and convenient protocol for synthesis of a-haloacrylates starting from phosphonium ylide and aldedyde or alcohol was described. Halodimethylsulfonium halide was used for the first time in halogenation of phosphonium ylide. Good yield as well as a
- Biao, Jiang,Ying, Dou,Xiangya, Xu,Min, Xu
-
p. 593 - 596
(2008/04/12)
-
- Fe(0)-mediated synthesis of tri- and tetra-substituted olefins from carbonyls: An environmentally friendly alternative to Cr(II)
-
Fe(0) was investigated as a cost-effective, environmentally friendly alternative to Cr(II) for the olefination of carbonyls by activated polyhalides. In many instances, Fe(0) was equivalent or superior to Cr(II). Notably, Fe(0), but not Cr(II), proved com
- Falck,Bejot, Romain,Barma, Deb K.,Bandyopadhyay, Anish,Joseph, Suju,Mioskowski, Charles
-
p. 8178 - 8182
(2007/10/03)
-
- Synthesis of dihalohydrins and tri- and tetra-substituted olefins
-
A novel synthesis reaction for highly stereospecific tri- and tetra-substituted olefins is described. A single stereoisomer of stable α-halo-α,β-ester is produced in high yield by the reaction of aldehyde or ketone with a trihalogenated compound such as t
- -
-
-
- (Z)-α-haloacrylates: An exceptionally stereoselective preparation via Cr(II)-mediated olefination of aldehydes with trihaloacetates
-
(Z)-α-Fluoro-, (Z)-α-chloro-, and (Z)-α-bromoacrylates were obtained with unprecedented yield and stereocontrol (>99%) via addition of the corresponding commercial trihaloacetates to aldehydes at room temperature using stoichiometric Cr(II) salts or catal
- Barma,Kundu, Abhijit,Zhang, Hongming,Mioskowski, Charles,Falck
-
p. 3218 - 3219
(2007/10/03)
-
- Addition of halogenoacetic esters to aldehydes and ketones in the presence of Fe(CO)5
-
The use of complex-forming solvents and variations in the reaction temperature made it possible to prepare α-halogeno β-hydroxy carboxylic esters upon addition of halogenoacetic esters to aldehydes and ketones promoted by iron pentacarbonyl.
- Terentiev,Vasilieva,Kuz'mina,Chakhovskaya,Brodsky,Belokon'
-
p. 722 - 723
(2007/10/03)
-
- The reactions of α,β-unsaturated esters by HCL/DMF/oxone system
-
The reactions of α,β-unsaturated esters by HCl/DMF/Oxone system afforded four different chlorinated products 2-5 in variable yields.
- Son, Ji Suk,Jung, Keum Shin,Kim, Hyoung Rae,Kim, Jae Nyoung
-
p. 1847 - 1855
(2007/10/03)
-
- Zinc metal-promoted stereoselective olefination of aldehydes and ketones with gem-dichloro compounds in the presence of chlorotrimethylsilane
-
A combination of zinc metal and a catalytic amount of chlorotrimethylsilane has been found to promote the transformation of various aldehydes and ketones with gem-dichloro compounds, such as benzylidene dichloride (1a) and methyl dichloroacetate (1b), to the corresponding cross- coupling products, such as substituted styrene 3 and methyl acrylates 4 derivatives, under mild reaction conditions in THF. The E-isomer of the corresponding alkenes was obtained stereoselectively in good-to-excellent yields. The reaction serves as a very convenient one-pot procedure.
- Ishino, Yoshio,Mihara, Masatoshi,Nishihama, Shintaro,Nishiguchi, Ikuzou
-
p. 2669 - 2672
(2007/10/03)
-
- Stereoselective dehydrobromination of alkyl α-Br α-Cl-carboxylates
-
(Z)-Alkyl α-Cl-α,β-unsaturated esters are prepared in excellent yields by stereoselective dehydrobromination of alkyl α-Br-α-Cl-carboxylates with LiCl-Li2CO3 in dimethylformamide.
- Forti, Luca
-
p. 3023 - 3026
(2007/10/02)
-
- Process for the preparation of α-halocinnamate esters
-
Prepare esters of α-halocinnamic acid and related compounds in high yield under relatively mild conditions.
- -
-
-
- Method of producing L-phenylalanine
-
There is provided a method of producing L-phenylalanine in high optical purity which comprises treating an N-acylphenylalanine alkyl ester in L form, in the presence of water, with an enzyme capable of hydrolyzing the N-acylphenylalanine alkyl ester in L form to give L-phenylalanine.
- -
-
-
- Dehydroacetoxylation and Acetate Transesterification in the Reactions of erythro- and threo-Methyl 3-(Substituted acetoxy)-2-halogeno-3-phenylpropanoates with Triethylamine
-
The response of the rate of triethylamine-induced dehydroacetoxylation of methyl threo-3-acetoxy-2-halogeno-3-phenylpropanoate to the influence of substituents in the leaving group points to a change in mechanism from (E1cB)I to a concerted process of the carbanion type.On the other hand, the erythro-isomers seem to undergo elimination exclusively through a carbanionic pathway.The effect of the acetoxy substituents upon the competitive transesterification is discussed.
- Garay, Raul O.,Cabaleiro, Mercedes C.
-
p. 1643 - 1648
(2007/10/02)
-
- Reaction of Benzeneseleninyl Chloride with Olefins in the Presence of a Lewis Acid. A Novel One Step Vinylic Chlorination
-
In the presence of aluminum chloride benzeneseleninyl chloride was found to be an exellent vinylic chlorinating reagent of olefins under mild conditions.However, such olefins as styrene, trans-stilbene, and trans-1-phenylpropene afforded dichloro adducts under similar conditions.A plausible reaction mechanism involving positive chlorine intermediate is proposed.
- Kamigata, Nobumasa,Satoh, Takeshi,Yoshida, Masato
-
p. 449 - 454
(2007/10/02)
-
- Elimination from Diastereomeric Methyl 3-Acetoxy-2-halogeno- and 2,3-Dihalogeno-3-phenylpropanoates
-
The rates of elimination of a number of erythro- and threo-PhCHYCXHCO2Me in methanolic triethylamine have been measured.The kinetic evidence together with the stereochemical results suggest that elimination of the dihalogeno-compounds occurs by an (E1cB)I process for the erythro-substrates and by a concerted pathways for the threo-isomers.In the case of the acetoxy derivatives the former mechanism seems to be operative for both stereoisomers.
- Cabaleiro, Mercedes C.,Garay, Raul O.
-
p. 1473 - 1476
(2007/10/02)
-
- Mechanism of Dehydroacetoxylation of Methyl 3-Acetoxy-3-aryl-2-halogenopropanoates
-
The rate of sodium methoxide-induced dehydroacetoxylation of the diesters p-RC6H4CH(OAc)CXHCO2Me (X= Br or Cl) has been studied as a function of the para-substituent.The results correspond to the para-substituent effects expected for proton abstraction from C-2, as estimated from the diastereoisomerisation of model compounds under similar conditions.This suggests that the elimination occurs via a carbanion mechanism, with C(2)-H bond-breaking rate-determining.The apparent insensitivity of the kinetic behaviour to configuration differences, together with the response of the reactions to the effect of the 3-substituent, is interpreted in terms of inductive stabilisation by the 2-halogen atom, which tends to localise the incipient negative charge at C-2, inhibiting distortion of its tetrahedral geometry.
- Cabaleiro, Mercedes C.,Garay, Raul O.
-
p. 1091 - 1096
(2007/10/02)
-
- CHLORINATION OF ALKENES BY MANGANESE(III) CHLORIDE SPECIES
-
Several manganese(III) chloride species have been prepared in situ and used as effective chlorinating agents of alkenes.
- Donnelly, K. D.,Fristad, W. E.,Gellerman, B. J.,Peterson, J. R.,Selle, B. J.
-
p. 607 - 610
(2007/10/02)
-
- Trichloroacetate de methyle-trisdimethylaminophosphine-chlorure de magnesium : un nouveau systeme de reactifs pour la generation d'enolates dihalogenes
-
The reactin of trisdimethylaminophosphine at low temperature with methyl trichloroacetate in the presence of an aldehyde and magnesium chloride leads to the exclusive formation of an α,α-dichloro β-hydroxyester.The reaction performed with N-Boc-L-leucinal
- Hayon, Annie-Flore,Fehrentz, Jean-Alain,Chapleur, Yves,Castro, Bertrand
-
p. 207 - 210
(2007/10/02)
-
- SOLVENT SHIFTS INDUCED BY DIMETHYLSULPHOXIDE IN α-PROTON MAGNETIC RESONANCES OF CARBONYL COMPOUNDS
-
The chemical shifts of α- and β-proton resonances of a number of carbonyl compounds in carbon tetrachloride and dimethylsulphoxide have been determined.The magnitude of the effect of the solvent change on the α-proton resonances seems to vary directly wit
- Cabaliero, M. C.,Giagante, N. N.
-
p. 1829 - 1832
(2007/10/02)
-
- Wittig-type Reaction of Dimetallated Carbodianion Species as Produced by Zinc Reduction of gem-Polyhalogen Compounds in the Presence of Levis Acids
-
Treatment of R1COR2 with a suspension prepared from diiodomethane, trimethylaluminium and excess zinc in tetrahydrofuran at room temperature affords olefins R1R2C=CH2 in fair (R1,R2=alkyl) to good (R1=alkyl, R2=H) yields.The ketone methylenation is better carried with another system consisting of CH2Br2-Zn-TiCl4.Ketones and aldehydes are transformed into α-chloro α,β-unsaturated esters or α,β-unsaturated esters in good yields on treatment with methyl trichloroacetate or t-butyl dichloroacetate (ethyl dibromoacetate) in the presence of diethylaluminium chloride and zinc.
- Takai, Kazuhiko,Hotta, Yuji,Oshima, Koichiro,Nozaki, Hitosi
-
p. 1698 - 1702
(2007/10/02)
-