- Acylation of Fluorocarbethoxy-Substituted Ylids: A Simple and General Route to α-Fluoro β-Keto Esters
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(Fluorocarbethoxymethylene)tri-n-butylphosphorane (3) reacts with acid chlorides and anhydrides to form the corresponding carbon acylated phosphonium salt 4, and hydrolysis of 4 under mild basic conditions provides RCOCFHCOOEt (8) in moderate yields.The reaction is applicable to primary, secondary, tertiary, cyclic, aromatic, and ester-substituted acid chlorides.Acylation with ethyl chloroformate and ethyl chlorothioformate leads to the diesters CFH(COOEt)2 and EtSCOCFHCOOEt.Extension of this reaction sequence to perfluorinated and partially fluorinated acid chlorides did not proceed cleanly to give the expected phosphonium salts.However, the anion derived from (EtO)2P(O)CFHC(O)OEt reacts with RFCOCl to form the corresponding C-acylated phosphonates 10, and hydrolysis of 10 gives RFCOCFHCOOEt.
- Thenappan, Alagappan,Burton, Donald J.
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- Preparation of fluorinated alkenes in ionic liquids
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The utility of ionic liquids (8-ethyl-1,8-diazabicyclo[5,4,0]-7-undecene trifluoromethanesulfonate and 8-methyl-1,8-diazabicyclo[5,4,0]-7-undecene trifluoromethanesulfonate) as a safe recyclable reaction medium for the synthesis of α-fluoro-α,β-unsaturate
- Kitazume, Tomoya,Tanaka, Genji
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- ONE-POT SYNTHESIS OF α-FLUORO-α,β-UNSATURATED ESTERS FROM CHLOROMALONIC ESTER AND CARBONYL COMPOUNDS USING "SPRAY-DRIED" POTASSIUM FLUORIDE
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α-Fluoro-α,β-unsaturated esters were prepared by one-pot reaction between aldehydes or ketones and diethyl chloromalonate in the "spray-dried" potassium fluoride-sulfolane system.
- Kitazume, Tomoya,Ishikawa, Nobuo
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Read Online
- A facile and mild approach for stereoselective synthesis of α-fluoro-α,β-unsaturated esters from α-fluoro-β-keto esters via deacylation
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The highly stereoselective olefination reaction of α-fluoro-β-keto esters for the synthesis of α-fluoro-α,β-unsaturated esters has been developed. The olefination combines nucleophilic addition, intramolecular nucleophilic addition, and elimination in one step, as well as provides a facile synthetic approach to α-fluoro-α,β-unsaturated esters which are important units in many biologically active compounds and useful precursors in a variety of functional-group transformations.
- Qian, Jinlong,Yi, Wenbin,Lv, Meifang,Cai, Chun
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supporting information
p. 127 - 132
(2015/02/02)
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- Highly regioselective SN2′ reaction of β-fluoroallylic phosphates with organocopper reagents and its application to the synthesis of fluorine-containing carbocycles
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Treatment of β-fluoroallyl phosphates with 2.2 equiv. of organocuprates, prepared readily from 2.2 equiv. each of CuCN and organometallics (organolithium reagents, Grignard reagents, and organozinc reagents), in THF at -40 to 0 °C for 0.25 to 24 h gave γ-products in a highly regioselective manner. Thus obtained γ-adducts were subjected to the ring-closing metathesis, the corresponding cyclic fluoroalkenes being afforded in good yields.
- Nihei, Takashi,Kubo, Yusuke,Ishihara, Takashi,Konno, Tsutomu
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p. 110 - 121
(2015/03/04)
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- P[N(i-Bu)CH2CH2]3N: Nonionic Lewis base for promoting the room-temperature synthesis of α,β-unsaturated esters, fluorides, ketones, and nitriles using Wadsworth - Emmons phosphonates
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The bicyclic triaminophosphine P(RNCH2CH2) 3N (R = i-Bu, 1c) serves as an effective promoter for the room-temperature stereoselective synthesis of α,β-unsaturated esters, fluorides, and nitriles from a wide array of aromatic, aliphatic, heterocyclic, and cyclic aldehydes and ketones, using a range of Wadsworth-Emmons (WE) phosphonates. Among the analogues of 1c [R = Me (1a), i-Pr (1b), Bn (1d)], 1a and 1b performed well, although longer reaction times were involved, and 1d led to poorer yields than 1c. Functionalities such as cyano, chloro, bromo, methoxy, amino, ester, and nitro were well tolerated. We were able to isolate and characterize (by X-ray means; see above) the reactive WE intermediate species formed from 2b and 1c.
- Chintareddy, Venkat Reddy,Ellern, Arkady,Verkade, John G.
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supporting information; experimental part
p. 7166 - 7174
(2010/12/25)
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- Microwave-assisted one-pot synthesis of α-fluoro-α,β- unsaturated esters under solvent-free conditions
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A microwave-assisted approach for the synthesis of α-fluoro-α, β-unsaturated esters from ethyl bromofluoroacetate, aldehydes, and triphenylphosphine in the presence of Zn-Cu under solvent-free conditions was achieved. The reaction was accomplished within
- Ren, Aishan,Yang, Xiongjun,Hong, Jing,Yu, Xiaochun
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experimental part
p. 2376 - 2378
(2009/05/27)
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- Iridium-catalyzed asymmetric hydrogenation of fluorinated olefins using N,P-ligands: A struggle with hydrogenolysis and selectivity
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To broaden the substrate scope of asymmetric iridium-catalyzed hydrogenation, fluorine-functionalized olefins were synthesized and hydrogenated with iridium complexes. Preliminary results showed high levels of fluorine elimination together with low selectivity. The loss of vinylic fluorine at first seemed difficult to handle, but further studies revealed that a catalyst with an azanorbornyl scaffold in the ligand gave more promising results. With this in mind, a new ligand was developed. This gave among the best results published to date for fluorine asymmetric hydrogenation, yielding high conversion and very high ee's with very little fluorine elimination. Further increasing the selectivity, the trials also revealed that tetrasubstituted fluorine-containing olefins can be hydrogenated with high ee's, despite that this class of compounds has usually shown low reactivity in this reaction type. Copyright
- Engman, Mattias,Diesen, Jarle S.,Paptchikhine, Alexander,Andersson, Pher G.
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p. 4536 - 4537
(2007/10/03)
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- The one-pot Wittig reaction: A facile synthesis of α,β- unsaturated esters and nitriles by using nanocrystalline magnesium oxide
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Nanocrystalline magnesium oxide was found to be an effective heterogeneous, solid base catalyst for the one-pot Wittig reaction to afford α,β-unsaturated esters and nitriles in excellent yields with high E-stereoselectivity in the presence of triphenylphosphine under mild conditions.
- Choudary, Boyapati M.,Mahendar, Koosam,Kantam, M. Lakshmi,Ranganath, Kalluri V. S.,Athar, Taimur
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p. 1977 - 1985
(2007/10/03)
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- Tandem reduction-olefination of triethyl 2-acyl-2-fluoro-2-phosphonoacetates and a synthetic approach to Cbz-Gly-Ψ[(Z)-CF{double bond, long}C]-Gly dipeptide isostere
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(Z)-α-Fluoro-α,β-unsaturated esters (Z)-7a-f were stereoselectively prepared by a tandem reduction-olefination of triethyl 2-acyl-2-fluoro-2-phosphonoacetates 6a-f with NaBH4 in EtOH. A concise synthesis of Cbz-Gly-Ψ[(Z)-CF{double bond, long}C]-Gly (26) as a dipeptide isostere was achieved via the tandem reduction-olefination of the corresponding 2-acyl-2-fluoro-2-phosphonoacetate 20.
- Sano, Shigeki,Kuroda, Yoko,Saito, Katsuyuki,Ose, Yukiko,Nagao, Yoshimitsu
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p. 11881 - 11890
(2007/10/03)
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- Efficient synthesis of fluoroalkenes via diethylzinc-promoted wittig reaction
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The synthesis of α-fluoroacrylates and α-bromo-α- fluoroalkenes was achieved in very good yields using aldehydes and ketones, triphenylphosphine, diethylzinc as promoter, and ethyl dibromofluoroacetate or dibromofluoromethane, respectively. A change in th
- Zoute, Ludivine,Dutheuil, Guillaume,Quirion, Jean-Charles,Jubault, Philippe,Pannecoucke, Xavier
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p. 3409 - 3418
(2008/02/11)
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- Microreactors for the synthesis of fluorinated materials
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The utility of microreactor for the synthesis of α-fluoro-α, β-unsaturated esters, trifluoromethylation and Michael addition reaction, is described.
- Miyake, Noriaki,Kitazume, Tomoya
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p. 243 - 246
(2007/10/03)
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- New reaction mode of the Horner-Wadsworth-Emmons reaction for the preparation of α-fluoro-α,β-unsaturated esters
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Excellent E-selectivity was observed in the Horner-Wadsworth-Emmons (HWE) reactions of ethyl 2-fluoro-2-diethylphosphonoacetate 1 with alkyl aryl ketones 2a-f using Sn(OSO2CF3)2 and N-ethylpiperidine. Mg(II)-promoted HWE r
- Sano, Shigeki,Ando, Tsuyoshi,Yokoyama, Kenji,Nagao, Yoshimitsu
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p. 777 - 779
(2007/10/03)
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- Stabilized haloylides: Synthesis and reactivity
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This paper describes simple and successful methods for the preparation of stabilized halogenated phosphoylides and discusses their stability, reactivity, and utility in organic synthesis. Preparations of several halogenated compounds including pharmaceutically interesting enol lactones are reported.
- Kayser, Margaret M.,Zhu, Jun,Hooper, Donald L.
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p. 1315 - 1321
(2007/10/03)
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- An Expedient Stereoselective Access to (Z)-2-Fluoroalkenoates
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The reaction between an aldehyde R-CHO and diethyl 2-oxo-3-fluorobutan-1,4-dioate as its sodium salt EtO2C-CO-CF-CO2Et-,Na+ mainly leads in THF to (Z)-2-fluoroalkenoates R-CH=CF-CO2Et (Z/E>/=80/20), the Z-stereoselectivity depending on the bulk of the R group.Key words: 2-Fluoroalkenoates; (Z)-stereoselective synthesis.
- Clemenceau, Denis,Cousseau, Jack
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p. 6903 - 6906
(2007/10/02)
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- A convenient palladium-catalyzed synthesis of α-fluoro-α,β-unsaturated esters
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During the treatment of ethyl α-fluoro-α-iodoacetate with aldehydes in the presence of tri-n-butylarsine and a catalytic amount (10 molpercent) of Pd(PPh3)4, the aldehydes were eventually completely consumed and α-fluoro-α,β-unsaturated esters were obtained in 52-90percent yield.
- Shen, Yanchang,Zhou, Yuefen
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p. 247 - 251
(2007/10/02)
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- Simmons-Smith reactions of fluoroallyl alcohol derivatives
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Simmons-Smith reactions of fluoroallyl alcohols and their derivatives with excess Zn-Cu and CH2I2 or Et2Zn and CH2I2 provided fluorocyclopropane derivatives. Diastereoselective cyclopropanation of the
- Morikawa,Sasaki,Mori,Shiro,Taguchi
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p. 3189 - 3193
(2007/10/02)
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- Synthesis of fluorinated enynes and dienes via 1-bromo 2-fluoro alkenes
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A stereospecific synthesis of fluorinated enynes and dienes was performed through palladium-catalyzed condensation of 1-bromo-2-fluoroalkenes, synthesized either through 'BrF' addition to the corresponding alkynes or through bromine addition and HBr elimi
- Eddarir,Mestdagh,Rolando
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- Reduction-Olefination of Esters: A New and Efficient Synthesis of α-Fluoro α,β-Unsaturated Esters
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A reduction-olefination sequence has been used to convert esters to α-fluoro α,β-unsaturated esters.In the presence of diisobutylaluminum hydride, esters are reduced to aldehydes that react in situ with -Li+ to form the title compounds in good yield with high stereoselectivity.The reaction is applicable to aliphatic, aromatic, cyclic, unsaturated, perfluorinated, and partially fluorinated esters.The E/Z ratio of unsaturated esters formed in the reaction varies with the cations present in the reaction mixture.Solvents have very little influence on stereochemistry.The sequential transformation of PhC(O)OBun to (E)-PhCH=CFC(O)OEt and then to (E,E)-PhCH=CFCH=CFC(O)OEt illustrates the scope of this methodology, which introduces a fluorine atom adjacent to an ester functionality with concomitant elongation of the chain by two carbon atoms.
- Thenappan, Alagappan,Burton, Donald J.
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p. 4639 - 4642
(2007/10/02)
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- Preparation et spectres de RMN, H, F et C-13 d'esters α-fluoro-cinnamiques para- et meta-substitues
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In this publication we present H, F and C-13 NMR spectra of a series of para (11 examples) and meta (7 examples) substituted α-fluoro-Z-cinnamic esters and their corresponding acids.We also discuss the characteristics and scope of the various preparation
- Elkik, Elias,Francesch, Charlette
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p. 423 - 428
(2007/10/02)
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