- An efficient Darzens reaction promoted by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)
-
An efficient DBU promoted Darzens reaction utilising α-haloketones containing an enolizable α′-hydrogen is reported. This method diastereoselectively afforded the corresponding α,β-epoxy ketones good to excellent yields in an one-pot reaction without using any transition metals or additives. Furthermore, haloketones without an α′-hydrogen are also applicable in this reaction.
- Luo, Juan,Hu, Lanfang,Zhang, Minghao,Tang
-
supporting information
p. 1949 - 1951
(2019/07/03)
-
- Preparation method of alpha, beta-epoxy ketone compound
-
The invention provides a method for efficiently preparing an alpha, beta-epoxy ketone compound from alpha-hydrogen-containing alpha-halogenated ketone as a raw material and various aldehydes under theaction of DBU or DBN. Namely the method comprises the steps: slowly and dropwise adding a dichloromethane mixed solution of alpha-halogenated ketone and aldehydes into a dichloromethane solution of DBU or DBN under the conditions of inert gas shielding and 20 DEG C below zero, ending a reaction, and then, carrying out separation and purification to obtain the alpha, beta-epoxy ketone compound. The synthesis method provided by the invention is available in raw material, low in cost, simple and easily-controlled in operation, relatively few in side reactions, simple in aftertreatment, relatively high in product yield, capable of greatly reducing the production cost, relatively high in economic benefit and suitable for large-scale industrial production.
- -
-
Paragraph 0036-0039
(2019/07/29)
-
- Stereodivergent Access to Enantioenriched Epoxy Alcohols with Three Stereogenic Centers via Ruthenium-Catalyzed Transfer Hydrogenation
-
The resolution technique of stereodivergent reaction on racemic mixtures (stereodivergent RRM) was employed for the first time in ruthenium complex catalyzed transfer hydrogenation of racemic epoxy ketones, providing a new and very simple method that allows access to enantioenriched epoxy alcohols with three stereogenic centers in a one-step fashion. The protocol features simple reaction conditions, practical operation, ability to scale up, and broad group tolerance.
- Zhao, Zhifei,Bagdi, Prasanta Ray,Yang, Shuang,Liu, Jinggong,Xu, Weici,Fang, Xinqiang
-
supporting information
p. 5491 - 5494
(2019/08/01)
-
- Arylruthenium(III) Porphyrin-Catalyzed C-H Oxidation and Epoxidation at Room Temperature and [RuV(Por)(O)(Ph)] Intermediate by Spectroscopic Analysis and Density Functional Theory Calculations
-
The development of highly active and selective metal catalysts for efficient oxidation of hydrocarbons and identification of the reactive intermediates in the oxidation catalysis are long-standing challenges. In the rapid hydrocarbon oxidation catalyzed by ruthenium(IV) and -(III) porphyrins, the putative Ru(V)-oxo intermediates remain elusive. Herein we report that arylruthenium(III) porphyrins are highly active catalysts for hydrocarbon oxidation. Using catalyst [RuIII(TDCPP)(Ph)(OEt2)] (H2TDCPP = 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin), the oxidation of C-H bonds of various hydrocarbons with oxidant m-CPBA at room temperature gave alcohols/ketones in up to 99% yield within 1 h; use of [nBu4N]IO4 as a mild alternative oxidant avoided formation of lactone from cyclic ketone in C-H oxidation, and the catalytic epoxidation with up to 99% yield and high selectivity (no aldehydes as side product) was accomplished within 5 min. UV-vis, electrospray ionization-mass spectrometry, resonance Raman, electron paramagnetic resonance, and kinetic measurements and density functional theory calculations lend evidence for the formation of Ru(V)-oxo intermediate [RuV(TDCPP)(O)(Ph)].
- Shing, Ka-Pan,Cao, Bei,Liu, Yungen,Lee, Hung Kay,Li, Ming-De,Phillips, David Lee,Chang, Xiao-Yong,Che, Chi-Ming
-
supporting information
p. 7032 - 7042
(2018/06/12)
-
- Biomimetic Oxidative Deamination Catalysis via ortho-Naphthoquinone-Catalyzed Aerobic Oxidation Strategy
-
An ortho-naphthoquinone-catalyzed oxidative deamination reaction has been developed where the molecular oxygen and water serve as the sole oxidant and nucleophile. The current aerobic deamination reaction proceeds via the ketimine formation between ortho-naphthoquinones and amines followed by the prototropic rearrangement and hydrolysis by water, representing a biomimetic oxidative deamination of amine species in the human body by the liver and kidneys. The compatibility of ortho-naphthoquinone organocatalysts with molecular oxygen and water opens up a new biomimetic catalyst system that can function as versatile deaminases for a variety of amine-containing molecules such as amino acids and DNA nuclear bases.
- Golime, Gangadhararao,Bogonda, Ganganna,Kim, Hun Young,Oh, Kyungsoo
-
p. 4986 - 4990
(2018/05/14)
-
- Evidence of a Sole Oxygen Atom Transfer Agent in Asymmetric Epoxidations with Fe-pdp Catalysts
-
Iron complexes with chiral tetradentate ligands based on the pdp scaffold (pdp = N,N′-bis(2-pyridylmethyl)-2,2′-bipyrrolidine) are efficient and versatile catalysts for the highly enantioselective epoxidation of a wide range of olefins. The nature of the
- Cussó, Olaf,Serrano-Plana, Joan,Costas, Miquel
-
p. 5046 - 5053
(2017/08/17)
-
- Preparation method and applications of parthenolide analogues
-
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.
- -
-
Paragraph 0044; 0045; 0046; 0047; 0048
(2016/10/10)
-
- Metal-free, one-pot, sequential protocol for transforming ,-epoxy ketones to -hydroxy ketones and -methylene ketones
-
A new sequential, one-pot protocol for transforming 1,3-disubstituted 2,3-epoxy ketones to β;-hydroxy ketones and α-methylene ketones has been developed. Reaction of epoxy ketones with boron trifluoride etherate (BF3·OEt2) generates the cationic intermediates by regioselective epoxide ring opening and an acyl shift. Then, a treatment of these cations with 2-aryl-1,3-dimethylbenzimidazolines (DMBIH) results in formation of 1,2-disubstituted 3-hydroxy ketones. DMBIH serves as a hydride donor in the second step of this process. Finally, the β;-hydroxy ketones can be converted to 1,2-disubstituted 2-methylene ketones by treatment with methanesulfonic acid or a combination of methanesulfonyl chloride and triethylamine. Importantly, the sequential steps involved in formation of the α-methylene ketone products can be carried out in one pot.
- Hasegawa, Eietsu,Arai, Saki,Tayama, Eiji,Iwamoto, Hajime
-
p. 1593 - 1600
(2015/02/19)
-
- Green oxidation of alkenes in ionic liquid solvent by hydrogen peroxide over high performance Fe(III) Schiff base complexes immobilized on MCM-41
-
A series of Fe(III) Schiff base complexes immobilized on MCM-41 were prepared and characterized by various physicochemical and spectroscopic methods. The complexes were used for oxidation of cyclohexene by 30% hydrogen peroxide in the presence and absence of ethylmethyl imidazolium chloride (EMIM) ionic liquid as solvent. The immobilized complexes proved to be effective catalysts and generally exhibited much higher catalytic performance than their homogeneous analogue. Catalytic performance of the complexes was also found to be closely related to the Schiff base ligands used. Additionally, ion liquid solvent efficiently improved all the catalytic performances. Finally, the reaction was extended to different alkenes using the heterogeneous complex 2-L4. Among all the alkenes, those containing π-electron-withdrawing groups and trans-orientations exhibited lower tendency for oxidation.
- Goldani, Mohammad Taghi,Mohammadi, Ali,Sandaroos, Reza
-
p. 801 - 805
(2014/07/07)
-
- Highly enantioselective bioinspired epoxidation of electron-deficient olefins with H2O2 on aminopyridine mn catalysts
-
The asymmetric epoxidation of various electron-deficient olefins with H2O2 in the presence of a novel family of chiral bioinspired bipyrrolidine-derived aminopyridine manganese(II) complexes [LM II(OTf)2] is rep
- Ottenbacher, Roman V.,Samsonenko, Denis G.,Talsi, Evgenii P.,Bryliakov, Konstantin P.
-
p. 1599 - 1606
(2014/05/20)
-
- General metal-free baeyer-villiger-type synthesis of vinyl acetates
-
Oxone, a cheap, stable, and nonhazardous oxidizing reagent, transforms α,β-unsaturated ketones of defined stereochemistry into their corresponding vinyl acetates through a Baeyer-Villiger reaction. This process is general and straightforward, tolerating a
- Poladura, Belén,Martínez-Casta?eda, ángel,Rodríguez-Solla, Humberto,Llavona, Ricardo,Concellón, Carmen,Del Amo, Vicente
-
p. 2810 - 2813
(2013/07/11)
-
- 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
-
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
-
p. 162 - 165
(2013/02/21)
-
- PAA-supported Hantzsch 1,4-dihydropyridine ester: An efficient catalyst for the hydrogenation of α,β-epoxy ketones
-
A new type of water-soluble polymer-supported NADH co-enzyme model-PAA (polyacrylic acid)-supported Hantzsch 1,4-dihydropyridine ester (PAA-HEH) was designed and synthesized. Catalytic amount of the supported reagent was used in the hydrogenation of α,β-epoxy ketones to the corresponding β-hydroxy ketones and showed great catalytic efficiency in the reduction reaction. This PAA-HEH was an optimal potential for recycling use.
- Zhou, Xin-Feng,Wang, Peng-Fei,Geng, Ye,Xu, Hua-Jian
-
p. 5374 - 5377
(2013/09/12)
-
- Study on comparison of reducing ability of three organic hydride compounds
-
Selective reduction of three kinds of substrates were studied to evaluate the reducing abilities of N,N-dimethyl-benzimidazolidine (DMBI), 2-phenylbenzimidazoline (PBI) and 2-phenylbenzothiazoline (PBT). As hydride donors, these three five-membered heterocyclic compounds performed different reducing abilities depending on the substrates.
- Feng, Yi-Si,Yang, Chun-Yan,Huang, Qiang,Xu, Hua-Jian
-
p. 5053 - 5059
(2012/07/28)
-
- Functionalization of BINOL and application in the homo- and heterogeneous enantioselective epoxidation of α,β-unsaturated ketones
-
The selective functionalization of BINOL derivatives with 3-(dimethylamino)prop-1-yn-1-yl is described. The corresponding La and Yb complexes were evaluated toward the epoxidation of α,β-unsaturated ketones. The Yb-complexes display the highest catalytic activity and selectivity, affording the expected chiral epoxides in quantitative yields and up to 90% ee in homogeneous conditions, and 93% ee when supported on silica gel.
- El Kadiri, Moulay Youness,Framery, Eric,Andrioletti, Bruno
-
supporting information
p. 6335 - 6338
(2013/01/15)
-
- Scope and limitations of one-pot multistep reactions with heterogeneous catalysts: The case of alkene epoxidation coupled to epoxide ring-opening
-
The combination of two reactions in one-pot multistep system requires the compatibility not only between the catalysts of both reactions, but also between all the reaction components and conditions. In the case of the coupling of alkene epoxidation and epoxide ring opening, it has been possible to synthesize cyanohydrin and azidohydrin derivatives through a simple process that involves a one-pot multistep process by using a mixture of two heterogeneous catalysts, a silica-grafted Ti catalyst and ytterbium chloride, whose efficiency depends on the reactivity of the starting alkene. In addition, in some cases the mixture of catalysts can be recovered and reused in several one-pot multistep cycles. However, this system is not possible with electron-deficient alkenes, as the basic catalyst required for epoxidation has shown to be incompatible with the ring-opening process.
- Fraile, José M.,García, Nuria,Herrerías, Clara I.,Mayoral, José A.
-
experimental part
p. 15 - 20
(2012/07/03)
-
- Cis-dihydroxylation of alkenes with oxone catalyzed by iron complexes of a macrocyclic tetraaza ligand and reaction mechanism by ESI-MS spectrometry and DFT calculations
-
[FeIII(L-N4Me2)Cl2]+ (1, L-N4Me2 = N,N′-dimethyl-2,11-diaza[3.3](2,6) pyridinophane) is an active catalyst for cis-dihydroxylation of various types of alkenes with oxone at room temperature using limiting amounts of alkene substrates. In the presence of 0.7 or 3.5 mol % of 1, reactions of electron-rich alkenes, including cyclooctene, styrenes, and linear alkenes, with oxone (2 equiv) for 5 min resulted in up to >99% substrate conversion and afforded cis-diol products in up to 67% yield, with cis-diol/epoxide molar ratio of up to 16.8:1. For electron-deficient alkenes including α,β-unsaturated esters and α,β-unsaturated ketones, their reactions with oxone (2 equiv) catalyzed by 1 (3.5 mol %) for 5 min afforded cis-diols in up to 99% yield with up to >99% substrate conversion. A large-scale cis-dihydroxylation of methyl cinnamate (9.7 g) with oxone (1 equiv) afforded the cis-diol product (8.4 g) in 84% yield with 85% substrate conversion. After catalysis, the L-N4Me2 ligand released due to demetalation can be reused to react with newly added Fe(ClO4)2?4H2O to generate an iron catalyst in situ, which could be used to restart the catalytic alkene cis-dihydroxylation. Mechanistic studies by ESI-MS, isotope labeling studies, and DFT calculations on the 1-catalyzed cis-dihydroxylation of dimethyl fumarate with oxone reveal possible involvement of cis-HO-Fe V O and/or cis-O FeV O species in the reaction; the cis-dihydroxylation reactions involving cis-HO-FeV O and cis-O FeV O species both proceed by a concerted but highly asynchronous mechanism, with that involving cis-HO-FeV O being more favorable due to a smaller activation barrier.
- Chow, Toby Wai-Shan,Wong, Ella Lai-Ming,Guo, Zhen,Liu, Yungen,Huang, Jie-Sheng,Che, Chi-Ming
-
experimental part
p. 13229 - 13239
(2010/12/19)
-
- Polymer-supported Oxone and tert-butyl hydroperoxide: new reagents for the epoxidation of α,β-unsaturated aldehydes and ketones
-
Efficient, mild and selective epoxidation of α,β-unsaturated aldehydes and ketones was performed using polyvinylpyrrolidonesupported Oxone (Oxone/PVP) and ButOOH/PVP.
- Pourali, Ali Reza
-
experimental part
p. 113 - 115
(2010/06/19)
-
- Indium-promoted chemo- and diastereoselective allylation of α,β-epoxy ketones with potassium allyltrifluoroborate
-
A practical method for the chemo- and diastereoselective allylation of α,β-epoxy ketones has been developed by using the convenient air and moisture stable reagent potassium allyltrifluoroborate. Indium metal was found to promote addition in stoichiometric or catalytic amounts, to afford α,β-epoxyhomoallylic tertiary alcohols in high yields and diastereoselectivities, without competing ring-scission of the epoxide.
- Nowrouzi, Farhad,Janetzko, John,Batey, Robert A.
-
supporting information; experimental part
p. 5490 - 5493
(2011/02/27)
-
- Highly efficient epoxidation of electron-deficient olefins with tetrabutylammonium peroxydisulfate
-
The epoxidation of α,β-unsaturated carbonyl compounds such as enones and enals was efficiently achieved with tetrabutylammonium peroxydisulfate in the presence of equimolar amounts of hydrogen peroxide and NaOH in acetonitrile or methanol at 25 °C in excellent yields. Base-sensitive substrate such as cinnamaldehyde could be successfully epoxidized in short reaction time under mild reaction conditions.
- Yang, Seung Gak,Hwang, Je Pil,Park, Min Young,Lee, Kieseung,Kim, Yong Hae
-
p. 5184 - 5188
(2008/02/01)
-
- Facile epoxidation of α,β-unsaturated ketones with cyclohexylidenebishydroperoxide
-
Cyclohexylidenebishydroperoxide was successfully used as the oxygen source for the oxidation of α,β-unsaturated ketones for the first time. The corresponding epoxides were obtained in excellent yields under the Weitz-Scheffer reaction conditions.
- Jakka, Kavitha,Liu, Jinyun,Zhao, Cong-Gui
-
p. 1395 - 1398
(2007/10/03)
-
- Highly efficient catalysts for epoxidation mediated by iminium salts
-
A range of substituted dihydroisoquinolinium salts has been tested in the catalytic epoxidation of several alkenes. Catalyst loadings as low as 0.5 mol% have been used in the epoxidation of 1-phenylcyclohexene. Georg Thieme Verlag Stuttgart.
- Bulman Page, Philip C.,Buckley, Benjamin R.,Appleby, Louise F.,Alsters, Paul A.
-
p. 3405 - 3411
(2007/10/03)
-
- Preparation and regioselective SN2′ reaction of novel gem-difluorinated vinyloxiranes with RLi
-
A series of hitherto unknown 3,4-epoxy-1,1-difluorobutenes were prepared from the readily accessible α,β-epoxy ketones and these compounds were found to undergo regioselective SN2′ reactions with hard RLi nucleophiles occurring at the highly positively charged terminal fluorine-possessing sp2 carbon atom in quite sharp contrast to the cases of the corresponding nonfluorinated vinyloxiranes which only attained a low level of regioselectivity. Addition of HMPA substantially improved the products' olefinic stereoselectivity. Theoretical calculations were used to qualitatively explore the nature of selectivity in these reactions.
- Ueki, Hisanori,Chiba, Takashi,Yamazaki, Takashi,Kitazume, Tomoya
-
p. 7616 - 7627
(2007/10/03)
-
- Recyclable Polyurea-Microencapsulated Pd(0) Nanoparticles: An Efficient Catalyst for Hydrogenolysis of Epoxides
-
(Matrix presented) Pd nanoparticles (~2 nm in size) microencapsulated in polyurea is an efficient and recyclable catalyst for reductive ring-opening hydrogenolysis of epoxides, using either HCOOH/Et3N or H2 as a hydrogen donor.
- Ley, Steven V.,Mitchell, Claire,Pears, David,Ramarao, Chandrashekar,Yu, Jin-Quan,Zhou, Wuzong
-
p. 4665 - 4668
(2007/10/03)
-
- Convenient methods for the preparation of unsymmetrical double aldols
-
Double aldol reaction proceeded stereoselectively at one α-carbon of ketones to give α-(1-hydroxyalkyl)-β-hydroxyalkyl ketones (double aldols) in good to high yields by the following three methods: i) tin(II) trifluoromethanesulfonate-mediated aldol reaction of aldehydes with β-hydroxy ketones (mono-aldols) in the presence of tertiary amines, ii) samarium(II) iodide-mediated aldol reaction of aldehydes with alkyl or aryl oxiranyl ketones, iii) Sn(OTf)2- promoted aldol reaction of α-bromo ketones with aldehydes giving α-bromo-β-stannyloxy ketones which were then converted to titanium enolates on treatment with low-valent titanium. Double aldols were formed by subsequent reaction of the above titanium enolates with aldehydes in one-pot procedure. Further, small and medium-sized carbocyclic compounds whose ring skeletons were composed of double aldol structure were synthesized by SmI2-mediated intramolecular cyclization between oxiranyl ketone and aldehyde functions.
- Mukaiyama, Teruaki,Pudhom, Khanitha,Yamane, Keiko,Arai, Hidehiro
-
p. 413 - 425
(2007/10/03)
-
- Efficient electrophilic and nucleophilic epoxidations utilizing a sulfonylperoxy radical and peroxysulfate species
-
Reaction of superoxide anion radical (O2-. with o-nitrobenzenesulfonyl chloride yields a o-nitrobenzenesulfonyl peroxy radical with strong oxidizing ability, which is capable of oxidizing aryl methylene moieties to aryl ketones and relatively electron-rich alkenes regioselectively to epoxides. The oxidizing species is tentatively attributed to the o-nitrobenzenesulfonyl peroxy radical of structure 1. Tetrabutylammonium peroxydisulfate (TBA)2S2O8, 2) was prepared by the reaction of tetrabutylammonium hydrogen sulfate with potassium peroxydisulfate. The epoxidation of enals and enones, such as α,β-unsaturated aldehydes or ketones, was efficiently achieved with 2 in the presence of hydrogen peroxide and base in acetonitrile or in methanol at 25°C. A base-sensitive substrate, such as cinnamaldehyde, could be successfully epoxidized under mild reaction conditions and in short reaction time.
- Park, Min Young,Yang, Seung Gak,Kim, Yong Hae
-
p. 431 - 436
(2007/10/03)
-
- Mild and convenient epoxidation of α,β-unsaturated ketones by amberlyst A-26 supported hydroperoxide
-
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
-
p. 1237 - 1242
(2007/10/03)
-
- Synthesis of α,β-epoxy ketones from alkyl- and arylsubstituted cyclopropanols
-
A number of aliphatic and arylaliphatic α,β-epoxy ketones were prepared in good yields in a one-pot procedure by a manganese-catalyzed ring cleavage of 1-substituted and 1,2-disubstituted cyclopropanols with oxygen followed by dehydration of the resulting
- Kulinkovich,Astashko,Tyvorskii,Ilyina
-
p. 1453 - 1455
(2007/10/03)
-
- Epoxidation of α,β-Unsaturated Ketones Using Hydrogen Peroxide in the Presence of Basic Hydrotalcite Catalysts
-
The basic layered hydrotalcites have been used as catalysts for the epoxidation of α,β-unsaturated ketones in heterogeneous reaction media using hydrogen peroxide as an oxidant. A wide variety of α,β-unsaturated ketones were oxidized to the corresponding epoxyketones in excellent yields under mild reaction conditions. For example, 2-cyclohexen-1-one gave 2,3-epoxycyclohexanone in 91% yield at 40°C for 5 h with high efficiency in hydrogen peroxide. The catalytic activity of the hydrotalcites increased as the basicity of their surfaces increased. In the case of the epoxidation of less reactive substrates, adding a cationic surfactant such as n-dodecyltrimethylammonium bromide (DTMAB) to the above oxidation system accelerated the epoxidation reaction. These hydrotalcite catalysts were easily separated from the reaction mixture and were reusable.
- Yamaguchi, Kazuya,Mori, Kohsuke,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
-
p. 6897 - 6903
(2007/10/03)
-
- Highly chemo- and regioselective rearrangement of α,β-epoxy ketones to 1,3-dicarbonyl compounds in 5 mol dm-3 lithium perchlorate-diethyl ether medium
-
Epoxides from α,β-unsaturated ketones undergo highly chemo- and regioselective rearrangement to 1,3-dicarbonyl compounds in 5 mol dm-3 lithium perchlorate-diethyl ether medium by a 1,2-migration of the carbonyl group at ambient conditions. The Royal Society of Chemistry 1999.
- Sankararaman,Ncsakumar
-
p. 3173 - 3175
(2007/10/03)
-
- Microwave Promoted Epoxidation of α,β-Unsaturated Ketones in Aqueous Sodium Perborate
-
A series of α,β-unsaturated ketones has been treated with sodium perborate in water and 1,4-dioxane under microwave irradiation to produce α,β-epoxyketones in good yields.
- Sharifi, Ali,Bolourtchian, Mohammad,Mohsenzadeh, Farshid
-
p. 668 - 669
(2007/10/03)
-
- Cross-aldol reaction between benzaldehyde and β-phenyiselanyl enoxysilanes derived from phenyiselanylmethylketones
-
The BF3-mediated aldol reaction between benzaldehyde and β- phenyselanyl enoxysilanes I derived from α-phenylselanylmethylketones has led to syn aldols 2 and α,α-bis(phenylselarryl) ketones 3 as by-products. Using tetrabutylammonium fluoride, the syn and anti aldols 2a were formed from 1a. Syn, syn-2-phenylselanyl 1,3-diols 5a and 5d were obtained by borane reduction of aldols 2a and 2d respectively.
- Ponthieux, Sylvain,Outurquin, Francis,Paulmier, Claude
-
p. 4017 - 4020
(2007/10/03)
-
- Practical epoxidation of α,β-unsaturated ketones with tetra-n-butylammonium peroxydisulfate
-
α,β-Unsaturated ketones reacted with tetra-n-butylammonium peroxydisulfate in the presence of hydrogen peroxide and base in acetonitrile at 25 °C to give the corresponding epoxides in excellent yields.
- Kim, Yong Hae,Hwang, Je Pil,Yang, Seung Gak
-
p. 3009 - 3012
(2007/10/03)
-
- Generation and reaction of monocarbonyliodonium ylides: Ester exchange of (Z)-(β-acetoxyvinyl)iodonium salts with lithium ethoxide and synthesis of α,β-epoxy ketones
-
Reported here for the first time are the generation of monocarbonyliodonium ylides and their alkylidene-transfer reactions to aldehydes yielding α,β-epoxy ketones. Exposure of (Z)-(2-acetoxy-1-decenyl)iodonium bromide, prepared stereoselectively by sodium acetate-catalyzed Michael addition of acetic acid to (1-decynyl)(phenyl)iodonium salt, to EtOLi in THF at -78°C results in ester exchange to generate the monocarbonyliodonium ylide with the liberation of ethyl acetate. 1H NMR measurements indicate that the ylide is stable up to -30°C in THF-d8 but gradually decomposes at -20°C to 1-bromo-2-decanone. The monocarbonyliodonium ylide acts as an alkylidene-transfer agent to carbonyl compounds, and the reaction with aldehydes in THF-DMSO at -30°C gives α,β-epoxy ketones with E-isomers as a major product. With an α,β-unsaturated aldehyde, selective 1,2-addition to the carbonyl group was observed. The relative rates of the alkylidene-transfer reaction of this ylide for a series of ring-substituted benzaldehydes were measured. A Hammett correlation plot with the σ constants of substituents afforded the reaction constant ρ = 2.95 (r = 1.00), which indicates that the monocarbonyliodonium ylide is moderately nucleophilic in nature.
- Ochiai, Masahito,Kitagawa, Yutaka,Yamamoto, Shinji
-
p. 11598 - 11604
(2007/10/03)
-
- Oxidation of Alkenes and Sulfides with Transition Metal Catalysts
-
Alkenes and sulfides were oxidized with transition-metal catalysts.The oxidant sources include molecular dioxygen, air and iodosylbenzene.The metal ions Mn(III), Fe(III), Co(II) and Ni(II) were used.The catalysts 1-18 of 1,3-dioxo-, β-ketoimine- or salen-types were prepared and their efficacy was examined. 1,2-Dihydronaphthalene is most efficiently epoxidized with O2/Me2CHCHO or PhIO in the presence of Mn(III)-salen catalysts.The Ni(II)-, Co(II)- and Fe(III)-catalysts of either β-ketoimine- or salen-types are useful for epoxidation of styrene, (E)-stilbene and (E)-benzalacetone in the O2/Me2CHCHO system; these epoxidations are stereospecific without formation of corresponding diastereomeric epoxides.Oxidation of methyl p-totyl sulfide with O2/Me2CHCHO is facilitated by the 1,3-dioxo-catalyst Co(II)-1.Monooxidation is achieved with Me2CHCHO in equimolar proportions to give the corresponding sulfoxide, whereas overoxidation is realized with excess Me2CHCHO to give the sulfone.These epoxidation and sulfide oxidations all occur at 25 deg C and are complete in less than a day.Key Words: Oxidation; Transition metals; Alkenes; Sulfides; 1,3-Diketone; β-Ketoimine; Salen.
- Liao, Jen-Hai,Cheng, Kuang-Yuan,Fang, Jim-Min,Cheng, Ming-Chu,Wang, Yu
-
p. 847 - 860
(2007/10/03)
-
- Epoxidation of Chalcone Derivatives Using Diethylzinc or Diethylcadmium under an Oxygen Atmosphere
-
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
-
p. 1818 - 1827
(2007/10/03)
-
- Kinetics of oxidation of styryl ketones by pyridinium chlorochromate
-
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.
-
-
- Baker's Yeast-mediated Transformations of α-Keto Epoxides
-
αβ-Epoxy ketones on treatment with baker's yeast yield different types of products depending on their substitution.Small groups such as H or Me attached at the epoxy end protect that end from attack.Thus,1-acyl epoxides with H, methyl or propyl as the 2-e
- Meth-Cohn, Otto,Horak, R. Martinus,Fouche, Gerda
-
p. 1517 - 1528
(2007/10/02)
-
- A Novel Darzens-Type Reaction Promoted by Tributylstannylcarbamate
-
Stannylcarbamate 1 proved to be a selective agent for generating organotin(IV) enolates from α-halo ketones.Thus, a Darzens reaction was achieved under mild and neutral conditions.The reaction took place without any side reactions and even with aliphatic α-halo ketones bearing enolizable α'-hydrogens.Various types of α,β-epoxy ketones and esters were obtained in this one-pot reaction.The stereoselectivity of the reaction was influenced by changing the halogen substituent of the α-halo ketones and by additives.Moreover, the present method could be appliedto γ- and δ-halo ketones as enolate precursors, and five- and six-membered cyclic compounds were obtained.
- Shibata, Ikuya,Yamasaki, Hayahide,Baba, Akio,Matsuda, Haruo
-
p. 6909 - 6914
(2007/10/02)
-
- Synthesis of chiral epoxy alcohols by use of baker's yeast
-
Synthesis of optically active 3,4-epoxy-4-phenyl-2-butanols, which are expected to be useful intermediates for the synthesis of biologically active compounds such as β-blocker, was achieved by asymmetric reduction of 3,4-epoxy-4-phenyl-2-butanone with baker's yeast.
- Takeshita,Akutsu
-
p. 1381 - 1384
(2007/10/02)
-
- The reaction of trialkylstannylmethyllithium with α,β-epoxy ketones and α-chloro ketones
-
The reactions of trialkylstannylmethyllithium with α,β-epoxy ketones afforded mainly cyclopropanols, while α-chloro ketones afforded allyl alcohols and/or cyclopropanols, in varying amounts depending upon the molar ratio of the reagent to the substrate.
- Sato, Tadashi,Kikuchi, Toshihiro,Tsujita, Hiroshi,Kaetsu, Atsushi,Sootome, Norio,Nishida, Ken-Ichiro,Tachibana, Kazutaka,Murayama, Eigoro
-
p. 3281 - 3304
(2007/10/02)
-
- THE OXIDATION OF α-β-UNSATURATED KETONES IN AQUEOUS SODIUM PERBORATE
-
A series of α-β-unsaturated ketones has been prepared with sodium perborate in water and a cosolvent to produce the corresponding epoxides in good yield.The reaction constitutes a mild and convenient method for the synthesis of α-β-epoxyketones.
- Reed, Kathryn L.,Gupton, John T.,Solarz, Traci L.
-
p. 3579 - 3588
(2007/10/02)
-
- Trisubstituted (Stannylmethyl)lithium as a Methylene Double Anion Equivalent. Reaction with Esters
-
Trisubstituted (stannylmethyl)lithium reacts with electrophiles as a methylene double anion equivalent to produce enolates from esters.The reaction mechanism is discussed.
- Sato, Tadashi,Matsuoka, Hiroharu,Igarashi, Tsutomu,Minomura, Masafumi,Murayama, Eigoro
-
p. 1207 - 1212
(2007/10/02)
-
- A stereocontrolled approach to electrophilic epoxides
-
Lithium t-butyl hydroperoxide (easily generated by addition of an alkyl-lithium to anhydrous t-butyl hydroperoxide in THF solution) is a powerful reagent for the epoxidation of electrophilic alkenes at -20 to 0 °C under full stereocontrol. Thus αβ-unsaturated esters, sulphones, sulphoximines, and amides are readily epoxidised with complete regio- and stereo-specificity and with considerable chiroselectivity (20-100%) when appropriate chiral auxiliaries such as menthyl, 8-phenylmenthyl, or a camphor-sulphonamide derivative are used. Asymmetric αβ-unsaturated sulphoximines undergo epoxidation with 100% diastereoselectivity. The only exceptions to stereocontrol noted are heavily substituted maleate esters such as di-t-butyl maleate. The αβ-epoxy amides are shown to be valuable sources of the corresponding epoxy ketones by treatment with an organolithium, allowing a stereo- and chemoselective entry in high yield to these useful intermediates.
- Meth-Cohn, Otto,Moore, Clive,Taljaard, Heinrich C.
-
p. 2663 - 2674
(2007/10/02)
-
- THE REACTION OF α-STANNYLMETHYLLITHIUM WITH ESTERS
-
Ketonic compounds were prepared from esters using α-stannylmethyllithium as the reagent.
- Sato, Tadashi,Matsuoka, Hiroharu,Igarashi, Tsutomu,Murayama, Eigoro
-
p. 4339 - 4342
(2007/10/02)
-
- "SODIUM PERCARBONATE" (SPC) AS A HYDROGEN PEROXIDE SOURCE FOR ORGANIC SYNTHESIS
-
"Sodium percarbonate" (SPC) is an inexpensive, stable, safe and commercially available material which may be used as a hydrogen peroxide source for organic synthesis.Epoxidation, amine and sulfide oxidation reactions were simply performed with the solid reagent in moderate to excellent yield.
- Ando, Takashi,Cork, David G.,Kimura, Takahide
-
p. 665 - 666
(2007/10/02)
-
- Reactivities of Acylperoxy Radicals in the Photoreaction of α-Diketones and Oxygen
-
The photoepoxidation of olefins with α-diketones and oxygen has been studied mechanistically focusing on the reactivities of intermediate radicals.One mole of α-diketone resulted in the formation of 2 mol of epoxide together with 2 equiv of C-C cleavage of olefins.The photoepoxidation proceeds via acylperoxy radicals RCO3* and the C-C cleavage of olefins is caused by acyloxy radical RCO2*.The addition of RCO3* to olefins was found to be ca.105-fold faster than that of acylperoxy radical ROO*.The relative reactivities of olefins suggest that acylperoxy radicals behave as a strongly electrophilic radical.That is, ρ values of -1 (vs.?+) obtained in the photoepoxidation of substituted styrenes are of the same magnitude as those in the epoxidation with molecular peracids.Although the relative reactivities of olefins toward the photoepoxidation roughly parallel those for the peracid epoxidations, the additivity of methyl substituent is not always operative.This is explained by a steric retardation by too many substituents on the carbon attacked by RCO3* in addition to the relative stabilities of resulting adduct radicals between olefins and RCO3*.Since acylperoxy radicals are not reactive towards sulfides, sulfoxides, or pyridine, a selective epoxidation of double bonds is possible.The relative reactivities of olefins toward benzoyloxy and methylperoxy redicals revealed a much less electrophilic nature of these oxy radicals, the ρ values for styrenes being -0.1 to -0.2.
- Sawaki, Yasuhiko,Ogata, Yoshiro
-
p. 3344 - 3349
(2007/10/02)
-
- SYNTHETIC CONTROL LEADING TO CHIRAL COMPOUNDS
-
A highly diastereoselective cross aldol reaction is developed using divalent tin enolates formed from stannous trifluoromethanesulfonate and carbonyl compounds.The reaction is extended to a highly enantioselective cross aldol reaction employing chiral dia
- Mukaiyama, Teruaki,Iwasawa, Nobuharu,Stevens, Rodney W.,Haga, Toru
-
p. 1381 - 1390
(2007/10/02)
-
- Chromic Acid Oxidation of Some Oxiranes
-
Oxiranes derived from some alkenes, with olefinic bonds present in different stereoelectronic environments, have been treated with Cr(VI)-reagents.The major products obtained have been identified and their formation rationalized.In some cases, the method becomes synthetically useful for C-C bond cleavage.
- Krishna, R. R.,Chawla, H. P. S.,Dev, Sukh
-
p. 1190 - 1196
(2007/10/02)
-