- Pyrenediones as versatile photocatalysts for oxygenation reactions with: In situ generation of hydrogen peroxide under visible light
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Pyrenediones (PYDs) are efficient photocatalysts for three oxygenation reactions: Epoxidation of electron deficient olefins, oxidative hydroxylation of organoborons, and oxidation of sulfides via in situ generation of H2O2 under visible light irradiation, using oxygen as a terminal oxidant and IPA as a solvent and a hydrogen donor.
- Zhang, Yuannian,Yang, Xin,Tang, Haidi,Liang, Dong,Wu, Jie,Huang, Dejian
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supporting information
p. 22 - 27
(2020/01/13)
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- Application of chiral TADDOL ligand and rare earth metal amide in combined catalysis of asymmetric reaction
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The invention relates to application of chiral TADDOL ligand and rare earth metal amide in combined catalysis of asymmetric epoxidation reaction of chalcone compounds. According to the application, alpha, beta-unsaturated ketone shown in a formula (1) and tert-butyl hydroperoxide react in the presence of organic alkali under the combined catalytic action of a chiral TADDOL ligand shown in a formula (3) and rare earth metal amide in an anhydrous, oxygen-free and protective atmosphere to obtain the chiral epoxy compound shown in the formula (2) after the reaction is completed, wherein R1 is selected from hydrogen, alkyl, halogen, alkoxy, trifluoromethyl, nitro or cyano, R2 is selected from phenyl, substituted phenyl, naphthyl, furyl or thienyl; R3 and R4 are respectively and independently selected from alkyl, phenyl or R3 and R4 and carbon atoms connected with R3 and R4 form naphthenic base; Ar is phenyl, substituted phenyl, biphenyl or naphthyl; the molecular formula of the rare earth metal amide is RE [N (SiMe3) 2] 3. The method has the advantages of wide substrate application range, high yield and high enantioselectivity.
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Paragraph 0180-0183
(2020/11/23)
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- A highly enantioselective asymmetric Darzens reaction catalysed by proline based efficient organocatalysts for the synthesis of di- and tri-substituted epoxides
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A new class of easily available and readily tunable proline based chiral organocatalysts was found to efficiently catalyse an unprecedented highly enantioselective asymmetric Darzens reaction of α-chloroketones and substituted α-chloroketones with various
- Ashokkumar, Veeramanoharan,Siva, Ayyanar,Ramaswamy Chidambaram
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supporting information
p. 10926 - 10929
(2017/10/13)
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- Facile epoxidation of α, β-unsaturated ketones with urea-2,2-dihydroperoxypropane as a new oxidant
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Abstract: Various aromatic α, β-unsaturated ketones were successfully transformed into their corresponding epoxides using urea-2,2-dihydroperoxypropane as the oxygen source for the first time. The reactions were carried out under mild alkaline conditions at room temperature in high yields and short reaction times. Graphical Abstract: [Figure not available: see fulltext.]
- Khosravi, Kaveh,Naserifar, Shirin
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p. 323 - 328
(2017/01/10)
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- Metal-Free and Efficient Epoxidation of α,β-Unsaturated Ketones with 1,1,2,2-Tetrahydroperoxy-1,2-Diphenylethane as a Powerful Solid Oxidant
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1,1,2,2-Tetrahydroperoxy-1,2-diphenylethane was used for the efficient and metal-free epoxidation of various α,β-unsaturated ketones, carried out under mild alkaline conditions at room temperature.
- Khosravi, Kaveh,Naserifar, Shirin,Mahmoudi, Boshra
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p. 683 - 689
(2017/06/19)
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- One-Pot Aerobic Photooxidative Darzens Reaction from Styrene and Benzyl Alcohol via Phenacyl Iodide and Benzaldehyde by Using?- Iodine
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We report a one-pot protocol for the synthesis of α,β-epoxy ketones from benzyl alcohols and styrenes with molecular oxygen, visible light, and molecular iodine. This procedure involves simultaneous aerobic photooxidative transformation of a benzyl alcohol into a benzaldehyde and of a styrene into a phenacyl iodide, with a subsequent Darzens reaction in one pot. This is the first report of a one-pot oxidative Darzens reaction starting from benzyl alcohols and styrenes.
- Omura, Ryuji,Fujiya, Akitoshi,Yamaguchi, Eiji,Tada, Norihiro,Miura, Tsuyoshi,Itoh, Akichika
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p. 3971 - 3975
(2016/11/11)
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- Preparation method and applications of parthenolide analogues
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The invention relates to a preparation method and applications of parthenolide analogues, and belongs to the field of organic synthesis. On the basis of reserving the main active group alpha-methylene-gamma-lactone and epoxide structure of parthenolide, series of compounds are designed by changing its framework, and its in-vitro antitumor activity is tested. Series of parthenolide analogues having biological activity are synthesized by a simple method, wherein two compounds are nontoxic to normal cells.
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Paragraph 0044; 0045; 0046; 0047; 0048; 0055; 0056
(2016/10/10)
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- One-pot synthesis of chalcone epoxides - A green chemistry strategy
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Waste minimization is a very important aspect of an environmentally benign protocol. A one-pot consecutive process has been developed for chalcone epoxide synthesis that allows compounds to be prepared without having to isolate and purify the intermediates. The strategy utilizes consecutive Claisen Schmidt condensation and epoxidation reactions to prepare chalcone epoxides from substituted benzaldehydes and acetophenones in good yields.
- Ngo, Dalyna,Kalala, Mbelu,Hogan, Victoria,Manchanayakage, Renuka
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p. 4496 - 4500
(2014/08/05)
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- Efficient generation of hydrogen peroxide by aerobic photooxidation of 2-propanol using anthraquinone-2-carboxylic acid and one-pot epoxidation of α,β-unsaturated ketones
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We developed an efficient method for the generation of hydrogen peroxide by aerobic photooxidation of 2-propanol using anthraquinone-2-carboxylic acid and molecular oxygen in air and visible light from fluorescent lamps. One-pot epoxidation of α,β-unsaturated ketones using the generated hydrogen peroxide is also reported.
- Cui, Lei,Furuhashi, Sohei,Tachikawa, Yuma,Tada, Norihiro,Miura, Tsuyoshi,Itoh, Akichika
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p. 162 - 165
(2013/02/21)
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- Mild and convenient epoxidation of α,β-unsaturated ketones by amberlyst A-26 supported hydroperoxide
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The epoxidation of α,β-unsaturated ketones to the corresponding epoxy ketones, using amberlyst A-26 supported hydroperoxide, which is prepared in situ from (35%) hydrogen peroxide and amberlyst A-26(OH-), is described. Reactions were carried out at room temperature and the corresponding epoxides were isolated in excellent yields.
- Lakouraj,Movassagh,Bahrami
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p. 1237 - 1242
(2007/10/03)
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- Study of interactive free energy relationships on oxidation of phenyl styryl ketone and its substituted analogues by pyridinium chlorochromate in acid medium: A kinetic study
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Kinetics of oxidation of phenyl styryl ketones (PSK) by pyridinium chlorochromate (PCC) has been investigated in acetic acid (90% v/v) medium in the presence of HClO4 in the temperature range 322 - 333K. The rate law of the reaction is as follows: -d[PCC]/dt=kK1K2[PSK] [PCC] [H+]/1+K2[PSK] The rates are enhanced by electron-releasing substituents in both the phenyl rings and decreased by electron-withdrawing substituents. The mechanism proposed envisages attack on >C = Cx and qy are found to be 0.236 and 0.252 at 323K.
- Annapoorna,Prasad Rao,Sethuram
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p. 283 - 287
(2007/10/03)
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- Superactive Mg-Al-O-t-Bu hydrotalcite for epoxidation of olefins
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Epoxidation of unfunctionalised olefins and α,β-unsaturated ketones has been accomplished at an amazingly and unprecedented rate by superactive Mg-Al-O-t-Bu-hydrotalcite solid base catalyst prepared in our laboratory.
- Choudary,Lakshmi Kantam,Bharathi,Venkat Reddy
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p. 1203 - 1204
(2007/10/03)
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- Epoxidation of Chalcone Derivatives Using Diethylzinc or Diethylcadmium under an Oxygen Atmosphere
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Reaction of diethylzinc or diethylcadmium with chalcone derivatives under an oxygen atmosphere gave high yields of the corresponding epoxides.This interesting epoxidation reaction could be carried out in various organic solvents and proceeded very smoothly.In addition, diethylcadmium is more effective for this epoxidation reaction of α,β-unsaturated ketones under an oxygen atmosphere.
- Shi, Min,Itoh, Nobuhiro,Masaki, Yukio
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p. 1818 - 1827
(2007/10/03)
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- Kinetics of oxidation of styryl ketones by pyridinium chlorochromate
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The kinetics of oxidation of substituted styryl phenyl ketones and of substituted styryl methyl ketones by pyridinium chlorochromate (PCC) have been studied in 90percent acetic acid-10percent water (v/v) containing perchloric acid and NaClO4, at 30 deg, 40 deg, 50 deg and 60 deg C.The two reactions are first order each in ketones and PCC.The rate constants are well correlated with ?+ constants.The effects of varying and the percentage of acetic acid on the reaction rate have also been studied.A suitable mechanism has been proposed.
- Mithula, M. Chandra,Murugesan, V.,Ananthakrishnanadar, P.
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- Triphenylbismuthonium 2-Oxoalkylide, A Moderately Stabilized Bismuthonium Ylide: Generation and Reactions with Some Electrophiles
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Treatment of (2-oxoalkyl)triphenylbismuthonium tetrafluoroborates 3 with potassium tert-butoxide in tetrahydrofuran at -78 deg C produced triphenylbismuthonium 2-oxoalkylides 4, which readily underwent epoxidation with the aldehydes 5 to give the α,β-epoxy ketones 7 with highly trans selectivity.The ylide 4a reacted with dimedone 11, the sulfonic acid 13, the thiol 15 and the isocyanate 17 to afford the corresponding ketones 12, 14, 16 and 19 in moderate to good yields.Reaction of the ylide 4c with the α,β-unsaturated ketones 10 and 21 afforded the 1,2-dibenzoyl- and the 1,2,3-tribenzoyl- cyclopropanes 20 and 22, respectively, although the yields were low.In the presence of a catalytic amount of nitrosobenzene 23, the ylide 4a a unique decomposition to give the 2,2,7,7-tetramethyloct-4-ene-3,6-dione 24 in quantitative yield, while the reaction with the nitrile oxide 25 yielded the isoxazoline 26.In all of these reactions, triphenylbusmuthane 6 was the additional major product.
- Matano, Yoshihiro
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p. 2703 - 2710
(2007/10/02)
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- Solvent Microstructure Effect on Reaction Stereochemistry; Ring Opening of Chalcone Oxides
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The stereochemistry and kinetics of acid-catalysed ring-opening reactions of epoxides are reported.Predominant inversion is found in the usual hydroxylic solvents.As the nucleophilicity of the solvent diminishes and acidity increases, the stereochemistry changes to predominant retention.Electron-donating substituents also tend to favour retention.In mixed solvents, the solvent microstructure is altered, leading to net retention for nucleophiles such as methanol.The exception is dioxane-methanol, which gives enhanced inversion.Molecular mechanics calculations indicate an electrostatic preference for the retention route, but a steric preference for inversion.The activation parameters indicate a negative entropy for both inversion and retention paths.Possible reasons are discussed for the entropy of the retention route being in the range normally found for A2 reactions.
- Durham, Dana,Kingsbury, Charles A.
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p. 923 - 930
(2007/10/02)
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- CATALYTIC ASYMMETRIC DARZENS CONDENSATION IN THE PRESENCE OF BOVINE SERUM ALBUMIN.
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Darzens condensation of aromatic aldehydes with phenacyl halides in the presence of a catalytic amount of bovine serum albumin afforded the corresponding epoxyketones in up to 62percent e.e.
- Annunziata, Rita,Banfi, Stefano,Colonna, Stefano
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p. 2471 - 2474
(2007/10/02)
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- Synthetic Enzymes. Part 2. Catalytyc Asymmetric Epoxidation by means of Polyamino-acids in a Triphase System
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The asymmetric epoxidation of several chalcones and other electron-poor olefins, in the presence of catalytic amounts of poly-(S)-amino-acids in a triphase system with optical yields of up to 96percent is described.The influence of the molecular structure of the catalysts and substrates, the solvent, and the temperature on the stereochemistry is discussed.
- Julia, Sebastian,Guixer, Joan,Masana, Jaume,Rocas, Jose
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p. 1317 - 1324
(2007/10/02)
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- Kinetics of Epoxidation of α,β-Unsaturated Ketones in Methanol Medium
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The kinetics of epoxidation of α,β-unsaturated ketones by alkaline H2O2 in methanol in the temperature range 25-40 deg C has been studied.The addition follows second order kinetics.The results indicate that the concentration of NaOH has a significant effect on the reactivity.The effect of various substituents in these reactions show that electron-releasing groups attached to the β-carbon atom in the olefin diminish the rate and electron-attracting groups enhance it.The oxidative cleavage of a few substituted epoxychalkones by hydroperoxide anion has also been studied in methanol at 30 deg C.Adherence to second order kinetics is excellent in every case and the rates are slower than those of the corresponding chalkones.The stability of epoxides depends on the substituents; electron-releasing groups diminish the rate and electron-attracting groups enhance it as observed in the case of epoxidation.The reaction obeys the Arrhenius equation and the respective activation parameters have been calculated.The effect of solvent polarity on the rate of epoxidation has been studied.The differences in the rates in methanol and water as solvents have been explained on the basis of solvent-solute interaction.
- Rama Rao, D. Sri
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p. 786 - 789
(2007/10/02)
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