- Synthesis, Electronic Spectroscopy, and Photochemistry of Methacrolein Oxide: A Four-Carbon Unsaturated Criegee Intermediate from Isoprene Ozonolysis
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Ozonolysis of isoprene, one of the most abundant volatile organic compounds in the earth's atmosphere, generates the four-carbon unsaturated methacrolein oxide (MACR-oxide) Criegee intermediate. The first laboratory synthesis and direct detection of MACR-oxide is achieved through reaction of photolytically generated, resonance-stabilized iodoalkene radicals with oxygen. MACR-oxide is characterized on its first π? a? πelectronic transition using a ground-state depletion method. MACR-oxide exhibits a broad UV-visible spectrum peaked at 380 nm with weak oscillatory structure at long wavelengths ascribed to vibrational resonances. Complementary theory predicts two strong ?€? a? πtransitions arising from extended conjugation across MACR-oxide with overlapping contributions from its four conformers. Electronic promotion to the 11π? state agrees well with experiment, and results in nonadiabatic coupling and prompt release of O 1D products observed as anisotropic velocity-map images. This UV-visible detection scheme will enable study of its unimolecular and bimolecular reactions under thermal conditions of relevance to the atmosphere.
- Vansco, Michael F.,Marchetti, Barbara,Trongsiriwat, Nisalak,Bhagde, Trisha,Wang, Guanghan,Walsh, Patrick J.,Klippenstein, Stephen J.,Lester, Marsha I.
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Read Online
- Acetal Addition to Electron-Deficient Alkenes with Hydrogen Atom Transfer as a Radical Chain Propagation Step
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We describe a visible-light-promoted addition of a hydrogen atom and an acetal carbon toward various electron-deficient alkenes. 1,3-Dioxolane is converted to its radical species in the presence of persulfate and an iridium catalyst upon visible light irradiation, which then reacts with electron-deficient alkenes. The reaction operates via a radical chain mechanism, a less commonly observed pathway for this class of transformation. Hydrogen atom transfer from 1,3-dioxolane to α-malonyl radicals is corroborated by experimental and density functional theory studies.
- Chan, Wei Chuen,Vinod, Jincy K.,Koide, Kazunori
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p. 3674 - 3682
(2021/02/16)
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- Dynamic Kinetic Resolution of I-Substituted Cyclic β-Ketoesters via Asymmetric Hydrogenation: Constructing Chiral Cyclic β-Hydroxyesters with Three Contiguous Stereocenters
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An efficient asymmetric hydrogenation of racemic I-substituted cyclic β-ketoesters via dynamic kinetic resolution to provide chiral cyclic β-hydroxy esters with three contiguous stereocenters is reported. Using a chiral spiro iridium catalyst (R)-5 (Ir-SpiroSAP), a series of racemic I-Aryl/alkyl substituted cyclic β-ketoesters were hydrogenated to the corresponding chiral cyclic β-hydroxy esters in high yields (84-97%) with good to excellent enantioselectivities (69->99% ee) and cis,cis-selectivities (up to >99:1).
- Yang, Dan,Wu, Xiong,Zheng, Xiao-Jie,Xie, Jian-Hua,Zhou, Qi-Lin
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supporting information
p. 5153 - 5157
(2021/07/20)
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- Preparation of mono-substituted malonic acid half oxyesters (SMAHOs)
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The use of mono-substituted malonic acid half oxyesters (SMAHOs) has been hampered by the sporadic references describing their preparation. An evaluation of different approaches has been achieved, allowing to define the best strategies to introduce diversity on both the malonic position and the ester function. A classical alkylation step of a malonate by an alkyl halide followed by a monosaponification gave access to reagents bearing different substituents at the malonic position, including functionalized derivatives. On the other hand, the development of a monoesterification step of a substituted malonic acid derivative proved to be the best entry for diversity at the ester function, rather than the use of an intermediate Meldrum acid. Both these transformations are characterized by their simplicity and efficiency, allowing a straightforward access to SMAHOs from cheap starting materials.
- Condon, Sylvie,Le Gall, Erwan,Pichon, Christophe,Presset, Marc,Xavier, Tania
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supporting information
p. 2085 - 2094
(2021/09/02)
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- Apple flavor compound, preparation method thereof and food additive
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The invention relates to an apple flavor compound, a preparation method thereof and a food additive. The apple flavor compound has a structural formula shown as the specification, the apple flavor compound can be named as 1-(1-(1-(3, 3-dimethylcyclohexyl)ethyl)3-ethyl malonic acid malonate. Experiments prove that the compound has obvious mature sweet apple fragrance, can be used in food additiveswith apple fragrance, and provides a new source for the apple flavor compound.
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Paragraph 0064-0066; 0081; 0082; 0086; 0090; 0091
(2020/07/13)
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- Enantioselective α-Amination of Acyclic 1,3-Dicarbonyls Catalyzed by N-Heterocyclic Carbene
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Herein, we describe a method for the catalytic enantioselective α-amination of α-substituted acyclic 1,3-ketoamides and 1,3-amidoesters that affords the products possessing N-substituted quaternary stereocenters with a chiral N-heterocyclic carbene (NHC). The reaction is based on the utilization of an intrinsic Br?nsted base characteristic of NHC that enables the catalytic formation of a chiral ion pair comprising the enolate and the azolium ion. A series of challenging open-chain α-substituted 1,3-dicarbonyls are aminated via this method with ee's of ≤99%.
- Santra, Surojit,Maji, Ujjwal,Guin, Joyram
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supporting information
p. 468 - 473
(2020/02/04)
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- Preparation method of diethyl methylmalonate by taking heteropolyacid as catalyst
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The invention relates to a preparation method of diethyl methylmalonate by taking heteropolyacid as a catalyst. The method comprises the following steps: adding 2-cyanopropionic acid into ethanol fordissolving, controlling the molar ratio of 2-cyanopropionic acid to ethanol to be 1:(3-4), and transferring the obtained solution into a reaction kettle after dissolving; stirring at room temperature,adding the heteropolyacid catalyst, controlling the mass ratio of 2-cyanopropionic acid to the heteropolyacid catalyst to be 2:(1-2), controlling the temperature to be 65-80 DEG C, reacting for 3-4 h, and then ending the reaction; distilling to separate ethanol, adding ammonia water to neutralize, regulating the pH value to be neutral, and fractionating to obtain crude diethyl methylmalonate; andputting the crude diethyl methylmalonate into a rectifying tower, and carrying out reduced pressure rectification to obtain diethyl methylmalonate. Sulfuric acid is replaced with the heteropolyacid catalyst for an esterification reaction, so the method has the advantages of good selectivity, high catalytic activity, high regeneration speed and small corrosion to equipment.
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Paragraph 0013-0020
(2020/05/01)
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- A methyl acid diethyl ester preparation method
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The invention relates to the field of organic synthetic technology, in particular to a methyl acid diethyl ester preparation method. The present invention provides methyl malonic acid diethyl ester preparation method of the cyano acid hydrolysis, simple process flow; ethanol - thionyl chloride system to carry out the esterification can effectively avoid the use of toxic solvents, and can improve the yield of the final product. According to an embodiment of the record, the invention provides a preparation method, the yield of the DEMM ≥ 62.5%, and the purity is ≥ 98%.
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Paragraph 0061-0075
(2019/04/04)
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- Continuous synthesis method of diethyl methylmalonate
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The invention belongs to the technical field of organic synthesis, and specifically relates to a continuous synthesis method of diethyl methylmalonate. 2-chloropropionic acid is continuously cyanidedto obtain 2-cyanopropionic acid; 2-cyanopropionic acid and ethanol carry out esterification reactions under the action of sulfuric acid to obtain a crude product of diethyl methylmalonate directly inone step; and the finished product is obtained after steps of washing and distillation. The reaction process is simple, and the yields of hydrolysis and esterification are high.
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Paragraph 0011; 0012; 0013; 0014; 0015; 0016; 0017; 0018
(2019/01/08)
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- AlCl3 catalyzed coupling of: N-benzylic sulfonamides with 2-substituted cyanoacetates through carbon-nitrogen bond cleavage
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A new cross-coupling reaction of N-benzylic sulfonamides with 2-substituted cyanoacetates for the synthesis of 2-substituted benzylbenzene was reported. In the presence of AlCl3, a broad range of N-benzylic sulfonamides reacted smoothly with 2-substituted cyanoacetates to afford structurally diverse benzylbenzenes in moderate to excellent yields. The conversion could be enlarged to gram-scale efficiently. The practicability of this approach was further manifested in the synthesis of a related bioactive agent with high anti-inflammatory activity.
- Hu, Chen,Hong, Gang,Qian, Xiaofei,Kim, Kwang Rim,Zhu, Xiaoyan,Wang, Limin
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supporting information
p. 4984 - 4991
(2017/07/10)
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- 2 - methyl malonic acid diester synthetic method of the compound
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The invention discloses a synthetic method of 2-diester methylmalonate compounds, and relates to the technical field of carboxylic ester preparation. The synthetic method comprises steps as follows: C, sulfonic acid 2-ethyl N-cyanoethanimideate IV and cyanide react under the action of a solvent and a catalyst, and 2-methyl malononitrile V is obtained; D, 2-methyl malononitrile V and ROH react under the action of the solvent and concentrated sulfuric acid, and products of 2-diester methylmalonate compounds I are obtained, wherein MCN is cyanide, M is Na or K, ROH is alkyl alcohol, alkenyl alcohol or a fluoride group containing alcohol, is benzyl alcohol or benzyl alkyl, halogen or nitro substituted benzyl alcohol, or is phenol or C1-C5 containing alkyl, halogen or nitro substituted phenol. The method is unique, the reaction conditions are mild, the reaction process is basically free of by-products, the yield is high, adopted raw materials have extensive sources, and acetaldehyde can be used as the raw material; the synthetic method is applicable to industrial production.
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Paragraph 0064-0066
(2017/08/10)
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- Regio- and stereoselective synthesis of 2,3,5-trienoates by palladium-catalyzed alkoxycarbonylation of conjugated enyne carbonates
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Palladium-catalyzed carbonylation of 2,4-enyne carbonates in an alcohol and under balloon pressure of CO proceeds through 1,5-substitution to yield (E)-2,3,5-trienoates. The olefin geometry of the substrate is important to control the overall stereochemistry of this alkoxycarbonylation method. The reaction proceeds through successive formation of π-allylpalladium with an R3 group oriented syn and σ-allenyl palladium complexes.
- Karag?z, Ezgi ule,Ku, Melih,Akpinar, Gürkan Eray,Artok, Levent
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p. 9222 - 9230
(2014/12/11)
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- Palladium complexes with N-heterocyclic carbene ligands as catalysts for the alkoxycarbonylation of olefins
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Palladium catalysts, generated from Pd(OAc)2 and 2 equiv of N,N-dialkylbenzimidazolium iodide, are effective for the alkoxycarbonylation of olefins in high yields (>90%). Alkoxycarbonylation of 1-hexene in dimethylacetamide is achieved within 24 h at 110 C using 1 mol % catalyst, 1000 psi CO, and ethanol. Reactions can be prepared in air, without the need of an acid additive to produce ethyl 2-methylhexanoate and ethyl heptanoate in approximately a 2:1 ratio.
- Roberts, Gina M.,Pierce, Philip J.,Woo, L. Keith
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p. 2033 - 2036
(2013/05/21)
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- Copper(II) triflate catalyzed amination and aziridination of 2-Alkyl substituted 1,3-dicarbonyl compounds
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A method to prepare α-acyl-β-amino acid and 2,2-diacyl aziridine derivatives efficiently from Cu(OTf)2 + 1,10-phenanthroline (1,10-phen)-catalyzed amination and aziridination of 2-alkyl substituted 1,3-dicarbonyl compounds with PhI=NTs is described. By taking advantage of the orthogonal modes of reactivity of the substrate through slight modification of the reaction conditions, a divergence in product selectivity was observed. In the presence of 1.2 equiv of the iminoiodane, amination of the allylic C-H bond of the enolic form of the substrate, formed in situ through coordination to the Lewis acidic metal catalyst, was found to selectively occur and give the β-aminated adduct. On the other hand, increasing the amount of the nitrogen source from 1.2 to 2-3 equiv was discovered to result in preferential formal aziridination of the C-C bond of the 2-alkyl substituent of the starting material and formation of the aziridine product.
- Ton, Thi My Uyen,Tejo, Ciputra,Tiong, Diane Ling Ying,Chan, Philip Wai Hong
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experimental part
p. 7344 - 7350
(2012/06/16)
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- NOVEL PHARMACEUTICAL COMPOUNDS
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Novel compounds and pharmaceutical compositions are provided. In one aspect of the invention the compounds may be utilized in medical practice, for example, in treatment of cancer and immune disorders.
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Page/Page column 5-6
(2011/12/13)
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- Nickel-catalyzed arylative ring-opening of 3-methylenecycloalkane-1,1- dicarboxylates
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An arylative ring-opening reaction of cyclic allylmalonates with arylzinc reagents under nickel catalysis has been developed. Upon the ring-opening sp3C-sp3C bond cleavage, the allylic moiety serves as an allylic electrophile to reac
- Sumida, Yuto,Yorimitsu, Hideki,Oshima, Koichiro
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supporting information; experimental part
p. 2254 - 2257
(2010/07/17)
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- Sml2-mediated carbon-carbon bond fragmentation in a-aminomethyl malonates
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A new and efficient samarium diiodide-promoted carbon-carbon bond fragmentation reaction of α-aminomethyl malonates, taking place normally at room temperature and generating the corresponding deaminomethylation products In 74-94% yields, is reported. The presence of the amino group Is necessary for the success of the current transformation.
- Xu, Qiongfeng,Cheng, Bin,Ye, Xinshan,Zhai, Hongbin
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supporting information; experimental part
p. 4136 - 4138
(2009/12/30)
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- Pheromones and analogs from Neozeleboria wasps and the orchids that seduce them: a versatile synthesis of 2,5-dialkylated 1,3-cyclohexanediones
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Chiloglottone, a wasp pheromone and attractant of sexually deceptive Chiloglottis orchids, and several structural analogs were synthesized. The synthetic approach is facile, high yielding and versatile, enabling rapid divergence to generate dialkylated analogs of chiloglottone. The key transformation was an organocadmium-mediated desymmetrization of glutaric anhydride derivatives. This library of synthetic 2,5-dialkylated 1,3-cyclohexanediones may assist in future identification of natural products in further species.
- Poldy, Jacqueline,Peakall, Rod,Barrow, Russell A.
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p. 2446 - 2449
(2008/09/20)
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- Acylation through ketene intermediates
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Carboxylic acids possessing a strong electron-withdrawing group in the α-position undergo facile dehydration upon reaction with carbodiimides to form the corresponding substituted ketenes that can react in situ with alcohols providing esters in a high yield. The ketene formed by the treatment of ethyl 2-methylmalonate with DCC was trapped in situ by a [4+2] cycloaddition with a second DCC molecule. The chemoselectivity of the acylation through the ketene intermediates was found to be substantially different from that of conventional acylation reagents showing a very low sensitivity toward the steric bulk of alcohols. A comparison of the sensitivity of the acylation to the steric bulk of alcohols supports the presence of a pseudopericyclic pathway for the nucleophilic addition of alcohols to ketenes derived from ethyl malonic and diethylphosphonoacetic acid.
- Shelkov, Rimma,Nahmany, Moshe,Melman, Artem
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p. 8975 - 8982
(2007/10/03)
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- Synthesis of 2,3-disubstituted indoles by radical cyclization with hypophosphorous acid and its application to total synthesis of (±)-catharanthine
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Radical cyclization of o-alkenylthioanilides using hypophosphorous acid and AIBN in the presence of Et3N proceeded smoothly to furnish the corresponding 2,3-disubstituted indoles in high yields. Utilizing the newly developed cyciization condition, a stereocontrolled total synthesis of (±)-catharanthine has been completed.
- Reding, Matthew T.,Kaburagi, Yosuke,Tokuyama, Hidetoshi,Fukuyama, Tohru
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p. 313 - 330
(2007/10/03)
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- Effect of supramolecular inclusion on the 1,2-rearrangement of free radicals
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The free radicals 3-ethoxy-2-(ethoxycarbonyl)-3-oxopropyl (1′) and 3-ethoxy-2-(ethoxycarbonyl)-2-methyl-3-oxopropyl (2′) were generated by photolysis of perester precursors in i) hexane solution, ii) in the presence of β-cyclodextrin, and iii) in NaY zeolite. While free radicals in solution are reluctant to rearrange, they do so when encapsulated in β-cyclodextrin or NaY zeolite. The coenzyme-B12-dependent enzymic rearrangement of methylmalonyl-CoA to succinyl-CoA could be mimicked by photochemical generation of an analogue of the putative intermediate radical in a molecular container.
- Chen, Ying,Kervio, Eric,Retey, Janos
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p. 552 - 558
(2007/10/03)
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- Novel [1,N]-Carbon to Carbon Rearrangement of an Ester Group via Organotitanium Intermediates Wherein the N Varies from 2 to 5. Full Scope and Limitation Leading Predominantly to the Rearrangement
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Malonates and methanetricarboxylates having an unsaturated side chain such as 2, 12, 20, 22, 24, 31, or 37 underwent a new ester rearrangement reaction promoted by (η2-propene)Ti(O-i-Pr)2 to afford the succinate derivative 4 or α,β-unsaturated ester 17, 21, 23, 25, 34, or 38 via the migration of the ester group from its original bis- or tris-ester position to the acetylene- or olefin-litanium complex. It has been found that the side reactions competing with the desired migration are dealkylation of the side chain of the ester and a simple cyclization. The substrates and conditions which allow the ester migration a preferential path were determined as well as the scope and limitation of this reaction.
- Yamazaki, Takanori,Urabe, Hirokazu,Sato, Fumie
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p. 1673 - 1681
(2007/10/03)
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- Use of the Nonionic Superbase P(MeNCH2CH2)3N in the Selective Monoalkylation of Active-Methylene Compounds
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The symmetric active-methylene compounds CH2(CO2Et)2 and CH2[C(O)Me]2 are selectively monoalkylated in the presence of 1.1 equiv of a variety of alkyl halides and 1 equiv of the nonionic Superbase P(MeNCH2CH2)2N in 85-98% yields in 30 min at room temperature. The unsymmetrical active-methylene compound EtO2CCH2C(O)Me is selectively monoalkylated under the same conditions, except for the temperature, which is 0 °C, in 59-88% yields. The observation of selective C- rather than O-alkylation is rationalized in terms of the formation of an enolate whose negatively charged oxygen is sterically protected by a nearby HP(MeNCH2CH2)2N+ counterion in a tight ion pair.
- Arumugam, Subramaniam,McLeod, Dale,Verkade, John G.
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p. 3677 - 3679
(2007/10/03)
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- Reaktion von β,γ- und γ,δ-ungesaettigten Estern mit dem Ti(OiPr)4/2iPrMgCl-Reagens: Bildung von β-titanierten Estern, β-titanierten Cyclobutanonen oder Acyltitan-Verbindungen
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Keywords: Alkene; Alkine; Cyclisierungen; Cyclobutanone; Titanverbindungen
- Kasatkin, Aleksandr,Yamazaki, Takanori,Sato, Fumie
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p. 2091 - 2093
(2007/10/03)
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- Reductive alkylation of electronegatively-substituted alkenes by alkylmercury halides
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Photolysis of alkylmercury halides in the presence of electronegatively-substituted 1-alkenes yields adduct radicals [RCH2CH(EWG).] that in some cases react with RHgX to form RCH2CH(HgX)(EWG), e.g., EWG = (EtO)2PO or PhSO2. When the EWG is carbonyl or cyano, the resonance stabilized adduct radicals fail to react with the alkyl mercury halide. In these cases photolysis with RHgCl/KI in Me2SO leads to the adduct mercurial via reaction of the adduct radicals with RHgI2-. The reactions of tertiary-enolyl adduct radicals are inefficient with RHgX/KI, and disproportionation of the adduct radicals is the major reaction pathway. For secondary- or tertiary-adduct radicals the reductive alkylation products are formed in excellent yield by reaction with RHgCl and silyl hydrides in Me2SO solution in a process postulated to involve RHgH as an intermediate. The relative reactivities of a number of α,β-unsaturated systems toward t-Bu. have been measured by competitive techniques. The results demonstrate a high reactivity of s-cis enones relative to the s-trans conformers.
- Russell, Glen A.,Shi, Bing Zhi,Jiang, Wan,Hu, Shuiesheng,Kim, Byeong H.,Baik, Woonphil
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p. 3952 - 3962
(2007/10/02)
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- RETROVIRAL PROTEASE INHIBITORS
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Urea-containing hydroxyethylamine peptide compounds are effective as retroviral protease inhibitors, and in particular as inhibitors of HIV protease.
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- Organic Reducing Agents. Reduction of Electron Deficient Bromides by 1,2,2,6,6-Pentamethylpiperidine (PMP)/Mercaptoethanol
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1,2,2,6,6-pentamethylpiperidine (PMP) is shown to be an effective reducing agent for the radical chain conversion of primary bromoesters in these reactions to the corresponding esters.The problem of inefficient reduction of tertiary bromoesters in these reactions has been overcome by the addition of an alkyl thiol which mediates the hydrogen atom transfer between the two hindered alkyl centers.
- Amoli, Maryam,Workentin, Mark S.,Wayner, Danial D. M.
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p. 3997 - 4000
(2007/10/02)
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- Electrosynthesis of cyclopropane derivatives by a Perkin-type reaction
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Electrolysis of active methylene compounds at a Pt cathode in MeCN in the presence of vicinal dihaloalkanes leads to cyclopropane derivatives in yields up to 90percent.In the cases of CH-acids with low pKa it is expedient to apply more active dihaloalkanes, while for CH-acids with higher pKa the desired product yields may be raised using electrogenerated bases. - Key words: CH-acids; 1,2-dihaloalkanes; cyclopropanes; electrosynthesis; electroreduction; electronegative bases; azobenzene.
- Petrosyan, V. A.,Vasil'ev, A. A.,Tatarinova, V. I.
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- Synthesis and spectroscopic characterisation of 13C-labelled ubiquinone-0 and ubiquinone-10
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(1-13C)-, (2-13C)-, (3-13C)-, (3-13CH3)-, (4-13C)-, and (13CH3O)2-ubiquinone-10 and the corresponding (1-13C)-, (6-13C)-, (5-13C)-, (5-13CH3)-, (4-13C)-, and (13CH3O)2-ubiquinone-0 have been synthesised from simple labelled starting materials via a single reaction scheme.The ubiquinones have been characterised using mass spectrometry, 1H NMR and 13C NMR.The spectroscopic results indicate that, within experimental error, the syntheses have been accomplished without scrambling or dilution of label.All labelled ubiquinones have been synthesised on a decigram scale.
- Liemt, W. B. S. van,Steggerda, W. F.,Esmeijer, R.,Lugtenburg, J.
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p. 153 - 162
(2007/10/02)
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- Surface-mediated Solid-phase Reaction. Part 2. Highly Selective Mono- and Di-C-alkylation of 1,3-Dicarbonyl Compounds on the Surface of Alumina
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Highly selective mono- and di-C-alkylation of 1,3-dicarbonyl compounds with different, structurally varied alkyl halides has been achieved in high yields through a simple solvent-free reaction on the surface of alumina impregnated with sodium or potassium alkoxide.
- Ranu, Brindaban C.,Bhar, Sanjay
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p. 365 - 368
(2007/10/02)
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- SELECTIVE C-ALKYLATION OF 1,3-DICARBONYL COMPOUNDS
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Lithium hydroxide-mediated alkylation of 1,3-dicarbonyl compounds proves to proceed with high efficiency and selectivity.
- Antonioletti, Roberto,Bonadies, Francesco,Orelli, Liliana Raquel,Scettri, Arrigo
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p. 237 - 238
(2007/10/02)
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- Synthesis of a new chiral phase-transfer catalyst: Chemical activity in alkylation reactions
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A new chiral phase-transfer catalyst (3S,4S)-1-benzyl-1-methyl-3,4- pyrrolidin-diol-onium iodide (2) synthesized, is found to be more active than the conventional tetraaklylammonium salts in alkylation reactions on active methylene compounds under usual solid-liquid phase-transfer conditions.
- Valli,Sarma,Choudary
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p. 481 - 482
(2007/10/02)
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- An unusual synthesis of malonates
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The reaction of palladium diacetate, triethylamine, ethyl chlorocarbonate and carbon monoxide in acetonitrile at room temperature gives a good yield of diethyl malonate. By 13C labelling of each of the reagents in turn it has been proven that the methylene group of the malonate comes from an acetate originally bonded to PdII.
- Barton, Derek H. R.,Langlois, Pascal,Okano, Takashi,Ozbalik, Nubar
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p. 325 - 326
(2007/10/02)
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- Reactions of 2-, 3-, and 4-(N-Nitroso)methylaminopyridine with Esters Containing Active Methylene Groups
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2-N-Nitrosomethylaminopyridine but not 2-methylaminopyridine, 3-N-nitrosomethylamino- or 3-methylaminopyridine and 4-N-nitrosomethylamino- or 4-N-methylaminopyridine react with malonate esters to form the corresponding derivatives of carbamates, amides and dihydropyridines respectively.In the reaction of the 4-isomers with diisopropyl malonate small amounts of the corresponding carbamates was also formed.
- Kiriazis, L.,Kalatzis, E.,Alexandrou, N. E.
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p. 155 - 160
(2007/10/02)
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- Synthesis and Liquid Crystal Properties of Dimethylene Linked Compounds Incorporating the Cyclobutane or Spiroheptane Rings
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The preparation of sixteen dimethylene linked compounds is described heptane ring>, and a comparison is made between the transition temperatures of these compounds and those of the corresponding esters.This comparison once again highlights the fact that the cyclobutane ring should be regarded, in terms of its ability to promote nematic thermal stability, as a "chain stiffener rather than as a ring system.A comparison is also made of the nematic thermal stabilities of the trans-cyclobutane and the spiroheptane systems and of the trans-cyclohexane and the spiroundecane systems.
- Chan, L. K. M.,Gemmell, P. A.,Gray, G. W.,Lacey, D.,Toyne, K. J.
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p. 229 - 246
(2007/10/02)
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- The reaction of potassium tetracarbonylhydridoferrate with ethyl acrylate in ethanol
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The reaction of KHFe(CO)4 with an excess of ethyl acrylate in ethanol for 30 h at 70 deg C leads to ethyl propyonate (270percent with respect to iron) and diethyl 4-oxopimelate (40percent yield with respect to iron), whether in an atmosphere of CO or argon.These reactions are shown to proceed by regioselective addition of KHFe(CO)4, to ethyl acrylate to give an intermediate alkyl tetracarbonylferrate 2 (M=K), which has been isolated as the PPN+ salt.In situ protonation of 2 (or of the isomeric alkyltetracarbonylferrate 10) by the solvent, and reductive elimination of ethyl propionate generate a coordinatively unsaturated Fe(CO)4 species which, when quenched in situ, gives the corresponding Fe(CO4)(acrylate) complex 9.In the presence of K2CO3 and an excess of ethyl acrylate, 9 affords ethyl propionate in 120percent yield with respect to iron, which is consistent with observed pseudo-catalytic reduction of ethyl acrylate by KHFe(CO)4.The formation of diethyl oxopimelate is thought to involve the isomerisation of 2, followed by reaction of the resulting alkyltetracarbonylferrate 10 with ethyl acrylate.
- Brunet, Jean-Jacques,Passelaigue, Elisabeth
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p. 203 - 216
(2007/10/02)
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- Synthesis and liquid crystal properties of compounds incorporating cyclobutane, spiroheptane and dispirodecane rings
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A number of esters of structure (I) incorporating the cyclobutane, spiroheptane, or dispirodecane rings has been prepared using a diethyl malonate synthesis.Strict comparison of the liquid crystal behaviour amongst the three classes containing a terminal cyano-substituent was not possible because both the cyclobutanes and dispirodecanes are mixtures of cis- and trans-isomers; the spiroheptanes are racemic systems.Using preparative hplc, it was however possible to isolate the pure cis- and trans-isomers of two of the cyano-substituted cyclobutane esters (I; R = alkyl, -X- = --, Y = CN).From the physical data and the results for the corresponding spiroheptane esters, conclusions regarding the effects of these ring systems on liquid crystal behaviour were obtained.The pure cis- and trans-isomers of the cyclobutane ester (I, R = C3H7, -X- = --, Y = CN) have been assessed for the trends in both order parameter and viscosity with temperature; the results support the idea that idea that the trans-cyclobutane ring adopts a more planar conformation at higher temperatures.Keywords: cyclobutane- and related spiro-systems, cis-/trans-isomerism, order parameter, briefringence, viscosity, structure/property relations.
- Chain, L. K. M.,Gemmel, P. A.,Gray, G. W.,Lacey, D.,Toyne, K. J.
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p. 113 - 140
(2007/10/02)
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- Process for the preparation of monomethyl-substituted methylene compounds
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Monomethyl-substituted methylene compounds are obtained by reacting methylene compounds of the formula STR1 in which R1 and R2 independently of one another represent --CN, --CO--R3, --SO2 --R3 or --NO2 and R1 can additionally denote -aryl(R1)n, wherein R3 denotes --OH, alkyl, aralkyl, aryl, alkoxy, aralkoxy or aryloxy, or amino which is substituted by alkyl and/or aralkyl and/or aryl, and furthermore two radicals R3 together can be an alkylene group, the radical of an aliphatic diol or of an aliphatic diamine or the group --NH--CO--NH-- and n represents 1, 2 or 3, with formaldehyde and with hydrogen in the presence of a condensation catalyst and a hydrogenation catalyst at elevated temperature, the methylene compound being introduced into the liquid phase of the mixture of reactants in the course of the reaction.
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- SYNTHESES D'ESTERS OU D'ACIDES α-HALOGENES A PARTIR DES GEM DICYANO EPOXIDES.
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α-halogeno esters or α-halogenoacids were easily prepared by selective one pot reaction of gem-dicyano epoxides with halohydric acids in an alcoholic or aqueous media.
- Robert, A.,Jaguelin, S.,Guinamant, J. L.
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p. 2275 - 2282
(2007/10/02)
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- ALKYLATION OF MALONIC ESTER AND MONOALKYLMALONIC ESTERS UNDER THE CONDITIONS OF PHASE-TRANSFER CATALYSIS
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Simple procedures were developed for the monoalkylation of malonic ester in the potassium hydroxide-DMFA (DMFA-acetone)-triethylbenzylammonium chloride system and the alkylation of alkylmalonic esters to dialkylmalonic esters in the calcium oxide-DMFA system.
- Sukhanov, N. N.,Trappel', L. N.,Chetverikov, V. P.,Yanovskaya, L. A.
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p. 2288 - 2290
(2007/10/02)
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- THE RELEVANCE OF ESTER EXCHANGE IN OXALACETIC ESTERS TO THE DECARBONMONOXYLATION REACTION
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Oxalacetic esters undergo ester exchange at 120 deg C, at which temperature loss of CO does not occur.A new mechanism is proposed for the decarbonmonoxylation reaction.
- Fitzhugh, Anthony L.,Strauss, Richard S.,Brewer, Elizabeth N.,Glassman, Steven D.,Jones, Maitland
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p. 3911 - 3914
(2007/10/02)
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- NUCLEOPHILIC RING OPENING OF EPOXIDES BY CARBANIONS; NOVEL FORMATION OF CYCLOPROPANE DERIVATIVES IN A NON-POLAR SOLVENT
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Nucleophilic ring-opening of epoxides 2(a-d) with carbanions of different steric requirements under refluxing benzene afforded a single stereoisomer of the cyclopropane derivatives 4.The same reaction under refluxing ethanol gave the normal products, i.e. the trans-lactones 6.Mechanism and high stereoselectivity observed in the novel cyclopropane formation, and regiospecific cleavage of the cyclopropane carboxylic acids (in 4) have also been discussed in detail.
- Chatterjee, A.,Banerjee, D.,Banerjee, B.,Mallik, R.
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p. 2965 - 2974
(2007/10/02)
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- 277. Structure and Chemistry of Malonylmethyl- and Succinyl-Radicals. The Search for Homolytic 1,2-Rearrangements
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Malonylmethyl radical I and its thioester analogue II were generated by standard photolytic and thermolytic methods from perester and bromo precursors.The structures of I and II were examined by ESR spectroscopy and found to exist in preferred conformations.However, no indication for their rearrangement by 1,2-shift of either an ethoxycarboxyl or (ethylthio)carbonyl group to the corresponding succinyl radicals III and IV, respectively, was found at temperatures below -40 deg C.At higher temperatures of up to 140 deg C, the search for malonylmethyl -> succinyl rearrangement was examined by thorough-product analysis of the perester decomposition.There is evidence for the rearrangement of the radical I to III by photolysis and of the radical II to IV by thermolysis at 130 deg C in chlorobenzene to only a small extent.
- Aeberhard, Urs,Keese, Reinhart,Stamm, Erich,Voegeli, Ulrich-Christian,Lau, Willy,Kochi, Jay Kazuo
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p. 2740 - 2759
(2007/10/02)
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