- Flash photolysis of 2,2,6-trimethyl-4H-1,3-dioxin-4-one in aqueous solution: Hydration of acetylketene and ketonization of acetoacetic acid enol
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Acetylketene was produced by flash photolysis of 2,2,6-trimethyl-4H-1,3-dioxin-4-one in aqueous solution, and rates of hydration of the ketene to acetoacetic acid enol and subsequent ketonization of the enol were measured in this solvent across the acidity range [H+] = 1-10-13 M. Acetylketene proved to be a remarkably reactive substance, undergoing uncatalyzed hydration with the rate constant k = 1.5 x 106 s-1, some 104 times more rapidly than ketene itself: the acetylketene hydration reaction was also catalyzed weakly by hydroxide ion but not by hydrogen ion. Ketonization of acetoacetic acid enol was much slower with rates in the millisecond to second range. The reaction showed a complex rate profile that could be interpreted in terms of rate-determining carbon protonaton of the carboxylate-ionized form of the enol in the acid region and rate-determining carbon protonation of the doubly ionized carboxylate-enolate form in the basic region. Analysis of the data provided the acidity constant pQ(a) = 4.05 for the carboxylic acid group of the enol and pQ(a)(E) = 13.18 for its enolic hydroxyl group. (These acidity constants are concentration quotients referring to an ionic strength of 0.10 M). Combination of the present results with information on the enolization of acetoacetic acid available from the literature gave K(E) = 5.6 x 10-3, pK(E) = 2.25, as an estimate of the keto-enol equilibrium constant.
- Chiang,Guo,Kresge,Tee
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- Kinetic study of the neutral and base hydrolysis of diketene
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Diketene (4-methylene-2-oxetanone) is inactive as a carcinogen, although it is more reactive toward nucleophiles than the analogs b-propiolactone and b-butyrolactone, both of which are alkylating agents of known carcinogenicity. In the literature the lack of carcinogenic effects has been ascribed to the rapid hydrolysis of diketene, which could preclude its in vivo alkylating capacity. In this work, the kinetics of the neutral and alkaline hydrolysis of diketene in aqueous and different water-dioxane media have been studied. The following conclusions can be drawn: (i) The neutral hydrolysis of diketene is slightly faster than that of β-propiolactone and β-butyrolactone. (ii) The hydrolysis reaction of diketene is very slow when compared to its alkylation reaction of a DNA-model carcinogenicity. (iii) The diketene neutral hydrolysis rate constant increases with the water/dioxane ratio, the opposite occurring in base hydrolysis. Copyright
- Goemez-Bombarelli, Rafael,Gonzalez-Perez, Marina,Perez-Prior, Maria Teresa,Manso, Jose A.,Calle, Emilio,Casado, Julio
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- Tautomeric Equilibria in Acetoacetic Acid
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Tautomeric equilibria in acetoacetic acid have been examined by 1H NMR and found to be strongly solvent dependent.Values for enol tautomer range from less than 2percent in deuterium oxide to 49percent in carbon tetrachloride.Chemical shift data suggest that the enol tautomer is internally hydrogen bonded in the less polar solvents and that internal hydrogen bonding is unimportant for the keto tautomer.The acid probably exists in the keto form in the solid state.
- Grande, Karen D.,Rosenfeld, Stuart M.
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- Discrepancies in the reactivity pattern of azaenamines towards cinnamonitriles: Synthesis of novel aza-steroid analogues
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Azaenamine incorporating pyrazole-4-carboxylate is prepared and allowed to react with α,β-substituted nitriles. A new reactivity pattern was observed leading to the formation of substituted pyrazolo[4′,3′-5,6]pyrimido[2,1-a]phthalazine-9-carbonitriles, which can be considered as aromatic aza-steroid analogues.
- Ghozlan, Said A.S.,Abdelmoniem, Amr M.,Butensch?n, Holger,Abdelhamid, Ismail A.
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- Synthesis, characterization & biological studies of Mn(II), Fe(III) and Co(II) complexes of (Z)-1, 5-dimethyl-4-(2-(2-oxopropylidene) hydrazinyl)-2-phenyl-1H-pyrazol-3(2H)-one
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Mn(II), Fe(III) and Co(II) complexes of the hydrazone derived from 4-aminoantipyrine and ethylacetoacetate has been synthesized and characterized by elemental analysis, electrical conductance in non-aqueous solvents, spectroscopic data including FT-IR, electronic, Electrospray ionization mass and M?ssbauer as well as by thermogravimetric analysis. In all the complexes, the compound acts as neutral bidentate ligand, coordinating through the pyrazolone oxygen and azomethine nitrogen. A high spin octahedral geometry assigned to the Mn(II), Fe(III) and Co(II) complexes were further confirmed by magnetic moment data. Elemental analysis showed that Fe(III) complex composed of metal and ligand in a molar ratio of 1:1 whereas metal to ligand ratio in Mn(II) and Co(II) complexes were found to be 1:2. The complexes have also been screened for their antimicrobial and antioxidant activity. The MTT assay of the Co(II) complex was also carried out. Antiviral docking studies of the ligand was done against the native and mutant HIV-1 Reverse Transcriptase protein (PDB ID: 1RT2 and 1FK9) and the ligand showed significant inhibitory activity against both forms of the protein.
- Sreepriya,Kumar, Shubha S.,V, Sadasivan,S, Biju,Meena, Sher Singh
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- 3,4-DIHYDROXYPHENETHYL 3-HYDROXYBUTANOATE, PREPARATION AND USE THEREOF
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The present disclosure discloses a novel compound, 3,4-dihydroxyphenethyl 3-hydroxybutanoate, a method for preparing the same and use of the same, and in particular, a compound of formula I, use of the compound of formula I, optically pure isomers of the compound, a mixture of enantiomers in any ratio, or pharmaceutically acceptable salts thereof in preparing health food and drug for relieving brain fatigue, improving learning and memory abilities, and ameliorating mania mood related to brain fatigue.
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Paragraph 0108
(2021/03/19)
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- Synthesis method for preparing 3,5-dichloro-2-pentanone from methyl acetoacetate
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The invention discloses a synthesis method for preparing 3,5-dichloro-2-pentanone from methyl acetoacetate. The method comprises the following steps: S1: reactor preparation: preparing two reactors, namely a first reactor and a second reactor; S2, reactor cleaning: putting the first reactor and the second reactor into clear water for cleaning, flushing the first reactor and the second reactor after cleaning is completed, and drying the first reactor and the second reactor after flushing is completed; and S3, hydrolysis for salt formation: adding methyl acetoacetate into the first reactor, dropwise adding 30% caustic soda liquid under cooling of circulating water, and continuing to conducting a reaction for 6 hours after dropwise adding so as to obtain a hydrolyzed material. According to the synthesis method for preparing 3,5-dichloro-2-pentanone from methyl acetoacetate, working steps are rigorous, flammable and explosive materials are prevented from being used, safety is improved, reaction operations are reduced, reaction efficiency is improved, and cost is effectively reduced.
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Paragraph 0023-0027; 0031-0035; 0039-0043; 0047-0051; 0055
(2020/10/30)
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- Structural design, synthesis and substituent effect of hydrazone-N-acylhydrazones reveal potent immunomodulatory agents
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4-(Nitrophenyl)hydrazone derivatives of N-acylhydrazone were synthesized and screened for suppress lymphocyte proliferation and nitrite inhibition in macrophages. Compared to an unsubstituted N-acylhydrazone, active compounds were identified within initial series when hydroxyl, chloride and nitro substituents were employed. Structure-activity relationship was further developed by varying the position of these substituents as well as attaching structurally-related substituents. Changing substituent position revealed a more promising compound series of anti-inflammatory agents. In contrast, an N-methyl group appended to the 4-(nitrophenyl)hydrazone moiety reduced activity. Anti-inflammatory activity of compounds is achieved by modulating IL-1β secretion and prostaglandin E2 synthesis in macrophages and by inhibiting calcineurin phosphatase activity in lymphocytes. Compound SintMed65 was advanced into an acute model of peritonitis in mice, where it inhibited the neutrophil infiltration after being orally administered. In summary, we demonstrated in great details the structural requirements and the underlying mechanism for anti-inflammatory activity of a new family of hydrazone-N-acylhydrazone, which may represent a valuable medicinal chemistry direction for the anti-inflammatory drug development in general.
- Meira, Cássio S.,dos Santos Filho, José Maurício,Sousa, Caroline C.,Anjos, Pamela S.,Cerqueira, Jéssica V.,Dias Neto, Humberto A.,da Silveira, Rafael G.,Russo, Helena M.,Wolfender, Jean-Luc,Queiroz, Emerson F.,Moreira, Diogo R.M.,Soares, Milena B.P.
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p. 1971 - 1985
(2018/03/12)
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- MULTIBIOTIC AGENTS AND METHODS OF USING THE SAME
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Multibiotic agents are disclosed. The multibiotic agents may contain two or more moieties linked through bonds cleavable in vivo. The bonds cleavable in vivo can be ester bonds, amide bonds, azo bonds, glycosidic bonds, carbonate linkers, or carbamate linkers. The moieties can be alcohol cores, amine cores, and/or acyls. Also disclosed are compositions containing multibiotic agents and methods of using the multibiotic agents.
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Page/Page column 84; 85
(2019/01/06)
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- Stereoselective Coupling of N-tert-Butanesulfinyl Aldimines and β-Keto Acids: Access to β-Amino Ketones
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The reaction of chiral N-tert-butanesulfinyl aldimines with β-keto acids under basic conditions at room temperature proceeds with high levels of diastereocontrol, leading to β-amino ketones in high yields. Based on DFT calculations, an eight-membered cyclic transition state involving coordination of the lithium atom to the oxygens of carboxylate and sulfinyl units was proposed, being in agreement with the observed experimental diastereomeric ratios. The synthesis of the piperidine alkaloid (-)-pelletierine was successfully undertaken in order to demonstrate the utility of this methodology.
- Lahosa, Alejandro,Soler, Tatiana,Arrieta, Ana,Cossío, Fernando P.,Foubelo, Francisco,Yus, Miguel
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p. 7481 - 7491
(2017/07/26)
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- Direct synthesis of γ-pyrones by electrophilic condensation of β-ketoesters
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Triflic anhydride is a versatile electrophile that is able to activate poor nucleophiles. Herein, we show that readily available β-keto esters are activated by Tf2O furnishing γ-pyrones. Mechanistic studies suggest that this transformation proceeds via a double triflation, formation of an oxocarbenium intermediate and dealkylation promoted by a crucial nitrile additive.
- Rodrigues, Catarina A. B.,Misale, Antonio,Schiel, Florian,Maulide, Nuno
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supporting information
p. 680 - 683
(2017/01/25)
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- Chiral Squaramide-Catalyzed Enantioselective Decarboxylative Addition of β-Keto Acids to Isatin Imines
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An efficient chiral squaramide-catalyzed enantioselective decarboxylative addition reaction of β-keto acids to isatin imines has been developed. The reaction proceeds smoothly using 20 mol% of organocatalyst to afford the chiral 3-aminooxindoles in high yield and excellent enantioselectivities. (Figure presented.).
- Kaur, Jasneet,Kumari, Anita,Bhardwaj, Vimal K.,Chimni, Swapandeep Singh
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p. 1725 - 1734
(2017/05/22)
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- Anchimeric-Assisted Spontaneous Hydrolysis of Cyanohydrins Under Ambient Conditions: Implications for Cyanide-Initiated Selective Transformations
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Nitrile/cyanide hydrolysis is of importance from the perspective of organic chemistry, especially, prebiotic chemistry. Herein we report that cyanohydrins, generated by the reaction of cyanide with β-keto acids and γ-keto-alcohols, spontaneously hydrolyze
- Yerabolu, Jayasudhan Reddy,Liotta, Charles L,Krishnamurthy, Ramanarayanan
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supporting information
p. 8756 - 8765
(2017/06/30)
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- Organocatalyzed asymmetric synthesis of morphans
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A general effective organocatalyzed synthesis of enantioenriched morphans with up to 92% ee was developed. The morphan scaffold was constructed in a one-pot tandem asymmetric organocatalyzed Michael addition followed by a domino Robinson annulation/aza-Michael intramolecular reaction sequence from easily available starting materials.
- Bradshaw, Ben,Parra, Claudio,Bonjoch, Josep
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supporting information
p. 2458 - 2461
(2013/06/27)
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- Studies on synthesis of various N-substituted derivatives with different heterocycles and their herbicidal activity
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Coumarin 4-methyl acetates are oxidized to coumarin-4- methyl glyoxalate using SeO2. Unlike the oxidative decaboxylation observed in the case of coumarin-4-acetic acid, here the oxidation is very selective for active methylene group, without affecting the COOH group protected with ester function. The product thus formed is analogous to the phenyl glyoxalic acid methyl ester i.e. coumarin 4-methyl glyoxalate and can be a useful moiety for the various synthetic manipulations of heterocycles substituted at 4-position of the coumarin showing promising herbicidal activity. Different heterocycles substituted at 4-position of the coumarin moiety have been synthesized. The herbicidal activity of these compounds has been evaluated. Zea Mays and Green Gram have been used for pre-emergence and postemergence screening of the herbicidal activity.
- Mashelkar,Tungare, Shefali S.,Bhagat, Sachin
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experimental part
p. 315 - 320
(2011/04/27)
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- Novel chiral pyrrolidinone scaffolds derived from threonine with antibacterial activity
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The synthesis of chiral pyrrolidinones derived from threonine, making use of a Dieckmann or aldol ring closure, is described. Compounds were found to exhibit antibacterial activity, for which the correlation with various physiochemical parameters was examined. This chiral tetramate scaffold may provide a useful template for fragment-based drug design providing rapid access to novel antibacterial compound libraries.
- Anwar, Muhammad,Cowley, Andrew R.,Moloney, Mark G.
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scheme or table
p. 1758 - 1770
(2010/10/18)
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- Synthesis and chemical reactivity of new azaenamines incorporated the 4,5,6,7-tetrahydrobenzo[ b ]thiophene moiety: 3+3 atom combination
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Novel azaenamines incorporating a tetrahydrothiophene moiety were prepared. Michael addition of an azaenamine with ,-unsaturated nitriles took place to give [1]benzothieno[3,2:5,6]pyrimido[1,2-b]pyridazine (thia-triaza-benzo[a] fluorene) derivatives. The condensation with malononitrile resulted in the formation of a [1]benzothieno[3,2:5,6]pyrimido[1,2-b]pyridazine-4-carbonitrile. The azaenamine also reacted with aldehydes and piperidine to give Mannich products. Georg Thieme Verlag Stuttgart · New York.
- Abdelhamid, Ismail Abdelshafy,Darwish, Elham Sayed,Nasra, Miead Adel,Abdel-Gallil, Fathy Mohamed,Fleita, Daisy Hanna
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experimental part
p. 1107 - 1112
(2010/05/19)
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- TOTAL SYNTHESIS OF SALINOSPORAMIDE A AND ANALOGS THEREOF
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The present application relates to certain compounds and to methods for the preparation of certain compounds that can be used in the fields of chemistry and medicine. Specifically, described herein are methods for the preparation of various compounds and intermediates, and the compounds and intermediates themselves. More specifically, described herein are methods for synthesizing Salinosporamide A and its analogs that includes forming a compound of formula (VIII).
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Page/Page column 45
(2009/09/28)
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- Compounds Useful In Therapy
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Compounds of Formula (I): and pharmaceutically acceptable salts, solvates (including hydrates) of said compounds and salts, or prodrugs of said compound, or pharmaceutically acceptable salts or solvates of said prodrugs, wherein the substituents are as herein defined, are useful in therapy, for example they may be useful for treating progesterone-mediated conditions such as endometriosis, uterine fibroids (leiomyomata), menorrhagia, adenomyosis, primary and secondary dysmenorrhoea (including symptoms of dyspareunia, dyschexia and chronic pelvic pain), or chronic pelvic pain syndrome.
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Page/Page column 17
(2008/06/13)
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- Electroorganic synthesis in oil-in-water nanoemulsion: TEMPO-mediated electrooxidation of amphiphilic alcohols in water
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Oil-in-water nanoemulsions, consisting of TEMPO, amphiphilic alcohols, and water, offer unique reaction environments for electrooxidation of the alcohols to give the corresponding carboxylic acids in good to excellent yields. Georg Thieme Verlag Stuttgart.
- Yoshida, Tomonori,Kuroboshi, Manabu,Oshitani, Jun,Gotoh, Kuniaki,Tanaka, Hideo
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p. 2691 - 2694
(2008/02/12)
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- COMPOUNDS USEFUL IN THERAPY
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Compounds of formula (I), or a pharmaceutically acceptable derivative thereof, wherein R1 and R3 independently represent H, C1-6alkyl, C3-8cycloalkyl, or halogen; R2 represents C1-6alkyl, CF3 or aryl; a represents 1 or 2; R4, R5, R7 and R8 independently represent H, C1-6alkyl, C1-6alkyloxy, CN or halogen, or R4 and R5, or R7 and R8, together with the ring to which they are attached form an aryl or heterocyclic fused ring system; X represents C or N; Y represents CH2 or O; R6 represents H, CN or halo provided that, when X represents N, R6 is absent. The compounds are useful for treating endometriosis, uterine fibroids (leiomyomata), menorrhagia, adenomyosis, primary and secondary dysmenorrhoea (including symptoms of dyspareunia, dyschexia and chronic pelvic pain), or chronic pelvic pain syndrome.
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Page/Page column 17-18
(2010/11/27)
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- Compounds useful in therapy
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Compounds of formula (I), [image] or pharmaceutically acceptable derivatives thereof, wherein: R1 represents H, C1-6-alkyl, C1-6alkyloxy, C3-8cycloalkyl, or halo; R2 represents H, C1-6alkyl (optionally substituted by R3), phenyl (optionally substituted by CN), or Het; R3 represents OH, CN, Het, —R4—C1-6alkyl, or CONR5R6; R4 represents —CO2—, or —O—; R5 and R6 independently represent H, C1-6alkyl (optionally substituted by OR7) or C3-8cycloalkyl; R7 represents H or C1-6alkyl; Het represents a five or six membered aromatic heterocyclic group containing (i) from one to four nitrogen heteroatom(s) or (ii) one or two nitrogen heteroatom(s) and one oxygen or one sulphur heteroatom or (iii) one or two oxygen or sulphur heteroatom(s), said heterocyclic group being optionally substituted by one or more groups selected from CN and C1-6 alkyl; R8 represents C1-6alkyl, C1-6alkyloxy, C3-8cycloalkyl, or halo; R9 and R10 independently represent H, C1-6alkyl, C1-6alkyloxy, CN, CF3 or halo; may be useful for treating endometriosis, uterine fibroids (leiomyomata), menorrhagia, adenomyosis, primary and secondary dysmenorrhoea (including symptoms of dyspareunia, dyschexia and chronic pelvic pain), or chronic pelvic pain syndrome.
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Page/Page column 21
(2008/06/13)
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- 4-(3,5-DICYANOPHENOXY) PYRAZOLE DERIVATIVES FOR USE AS TRANSCRIPTASE MODULATORS IN THE TREATMENT OF I.A. HIV
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This invention relates to the pyrazole derivatives of formula (I) and pharmaceutically acceptable salt, solvate or derivatives thereof, to their use in medicine, to compositions containing them, to processes for their preparation and to intermediates used in such processes. The compounds of the invention bind to the enzyme reverse transcriptase and are modulators, especially inhibitors, thereof. Reverse transcriptase is implicated in the infectious lifecycle of Human Immunodeficiency Virus (HIV). Compounds which interfere with the function of this enzyme have shown utility in the treatment of conditions caused by HIV and genetically related retroviruses, such as Acquired Immune Deficiency Syndrome (AIDS).
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Page/Page column 19-20
(2010/02/06)
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- Pyrazole derivatives
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This invention relates to pyrazole derivatives of formula (I) or pharmaceutically acceptable salts, solvates or derivatives thereof, and to processes for the preparation thereof, intermediates used in their preparation of, compositions containing them and the uses of such derivatives. The compounds of the present invention bind to the enzyme reverse transcriptase and are modulators, especially inhibitors thereof. As such, the compounds of the present invention are useful in the treatment of a variety of disorders including those in which the inhibition of reverse transcriptase is implicated. Disorders of interest include those caused by Human Immunodificiency Virus (HIV) and genetically related retroviruses, such as Acquired Immune Deficiency Syndrome (AIDS).
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- A new protocol for a regioselective aldol condensation as an alternative convenient synthesis of β-ketols and α,β-unsaturated ketones
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A general and convenient synthesis of β-ketols and α,β-alkenones has been achieved by a Knoevenagel condensation of a β-ketoacid with an aldehyde in aqueous medium. Saponification of a β-ketoester by an aqueous KOH 10% solution gives the potassium salt of the β-ketoacid, which is condensed in situ with an aldehyde at pH 7.8-8.0, at 60 °C for 5-6 h. The intermediate β-ketocarboxylate is smoothly decarboxylated in the reaction medium, giving the β-ketol in high yield (75-90%). Acidification of the reaction mixture at pH 1 and heating at 70 °C under vigorous stirring for 6 h, leads directly to the corresponding α,β-unsaturated ketone in good yield (65-75%).
- Kourouli, Therapia,Kefalas, Panagiotis,Ragoussis, Nikitas,Ragoussis, Valentine
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p. 4615 - 4618
(2007/10/03)
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- Process for ring cleavage of thiazolidine derivatives
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Process for the hydrolytic ring cleavage of thiazolidine derivatives to give 2-aminomercaptan derivatives and carbonyl compounds, which comprises bringing an aqueous solution of the thiazolidine derivative into contact with an acidic cation exchanger in the H+form, giving a solution L1which contains the carbonyl compound and eluting the cation exchanger with a suitable eluent, giving a solution L2which contains the 2-aminomercaptan derivative.
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Page column 5
(2008/06/13)
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- A new approach to the synthesis of 3,6- and 5,6-dialkyl derivatives of 4-hydroxy-2-pyrone. Synthesis of rac-germicidin
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A new approach to the synthesis of 3,6- and 5,6-dialkyl-4-hydroxy-2- pyrones has been developed. The method includes the formation of acylated Meldrum's acids (5-(2-alkyl-3-oxoacyl)-2,2-dimethyl-1,3-dioxane-4,6-diones) followed by their thermal transformation. Introduction of 3-alkyl substituents was accomplished by acylation of 4-hydroxy-2-pyrones and ionic hydrogenation of the 3-acyl derivatives obtained. The effectiveness of this new approach has been demonstrated in the synthesis of rac-germicidin, an autoregulative germination inhibitor of Streptomyces viridochromogenes NRRL B-1551.
- Lokot, Igor P.,Pashkovsky, Felix S.,Lakhvich, Fedor A.
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p. 4783 - 4792
(2007/10/03)
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- The effect of metal ions on the reaction of hydrogen peroxide with Kraft lignin model compounds
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Peroxide bleaching is significantly affected by transition and alkaline earth metals. Isolating the effects of different transition and alkaline earth metals on the reactions of peroxide with different representative lignin structures allows the separation of the positive from the negative contributions of these metal ions. In this work, five monomeric or dimeric phenolic lignin model compounds were treated with alkaline hydrogen peroxide in the absence or presence of Mn2+, Cu2+, Fe3+, and Mg2+. We followed the disappearance of the starting material and the progress of demethylation, radical coupling and oxalic acid formation were followed. Transition metals increased the reactivities of all the lignin model compounds with hydrogen peroxide in the order Mn2+ > Cu2+ > Fe3+, which is the same as the order of activity toward peroxide decomposition while Mg2+ stabilized the system. Demethylation, radical coupling, and oxalic acid formation were all increased by the presence of transition metals in the system and decreased by the addition of Mg2+. The acceleration of the total degree of reaction and of the demethoxylation reactions improves peroxide bleaching, but the increase in the radical coupling reactions can affect the further bleachability of pulp while the increase in the formation of oxalic acid could lead to a greater probability of scaling.
- Sun, Yujun,Fenster, Michael,Yu, Annie,Berry, Richard M.,Argyropoulos, Dimitris S.
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p. 667 - 675
(2007/10/03)
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- Chemoselectivity in the Reactions of Acetylketene and Acetimidoylketene: Confirmation of Theoretical Predictions
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Acetylketene (1) was generated by flash pyrolysis of 2,2,6-trimethyl-4H-1,3-dioxin-4-one (6). The selectivities of 1 toward a number of representative functional groups were measured for the first time in a series of competitive trapping reactions. The trend in reactivities toward 1 follows the general order amines > alcohols aldehydes ≈ ketones and can be rationalized by considering both the nucleophilicity and the electrophilicity of the reacting species. Alcohols show significant selectivity based on steric hindrance, with MeOH ≈ 1° > 2° > 3°. These selectivities are consistent with the activation energies and the pseudopericyclic transition structure previously calculated for the addition of water to formylketene. The results, presented here, of ab initio transition structure calculations for the addition of ammonia to formylketene are qualitatively consistent with the experimental trends as well. N-Propylacetacetimidoylketene (2) was generated by the solution pyrolysis of tert-butyl N-propyl-3-amino-2-butenoate (9a) and showed similar selectivity toward alcohols as opposed to ketones and similar steric discrimination toward alcohols. This is again in agreement with previous ab initio calculations. Taken together, these experimental trends in the reactivities of both 1 and 2 toward a variety of reagents provide strong, although indirect support for the planar, pseudopericyclic transition structures for these reactions which are predicted by ab initio calculations.
- Birney, David M.,Xu, Xiaolian,Ham, Sihyun,Huang, Xiaomeng
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p. 7114 - 7120
(2007/10/03)
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- Catalytic Formation of Ketones via Double Alkylation of Carbon Monoxide Resulting from Reductive Disproportionation of Carbon Dioxide by 2+ (bpy = 2,2'-bipyridine, qu = quinoline)
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The title complex catalyzes reductive disproportionation of CO2 to afford CO and CO32- in the electrochemical CO2 reduction in the presence of LiBF4, while the same reduction in the presence of (CH3)4NBF4 in DMSO/CH3CN produced CH3COCH3, CH3COCH2COO-, and HCOO- as well CO and CO32-.
- Nakajima, Hiroshi,Mizukawa, Tetsuro,Nagao, Hirotaka,Tanaka, Koji
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p. 251 - 252
(2007/10/02)
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- NITROIMIDAZOLES XI. SYNTHESES OF SUBSTITUTED (1-METHYL-5-NITRO-2-IMIDAZOLYL)PYRAZOLES
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The β-diketone derivatives of nitroimidazole were synthesized from the reaction of magnesium salt of β-keto acids (2) with imidazolide (3).The β-keto acids (1) were obtained from the hydrolysis of β-keto esters (5) or the reaction of magnesium methylcarbonate with the ketone (6).The reaction of β-diketones (4) with hydrazine afforded the pyrazoles (7), which were converted to N-methylpyrazoles (8) and (9).The latters could also be obtained from the reaction of β-diketones (4) with methylhydrazine.
- Karimi-Khoozani, Rahim,Ghanbarpour, Alireza,Shafiee, Abbas
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p. 503 - 510
(2007/10/02)
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- A Study of the Ferrous Ion-initiated SRN1 Reactions of Halogenoarenes with tert-Butyl Acetate and N-Acylmorpholine Enolates
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A detailed preparative study is reported of the ferrous ion-initiated SRN1 reactions of a range of halogenoarenes with the sodium enolates of tert-butyl acetate, n-acetylmorpholine and a number of higher N-acylmorpholines.Smooth and rapid substitution occurs in many cases, and good to excellent yields were obtained of arylacetic esters or acids, arylacetamides and arylalkanamides.The broad scope and limitations of the process have been defined, and the possible role of the ferrous ion is discussed.
- Leeuwen, Milko van,McKillop, Alexander
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p. 2433 - 2440
(2007/10/02)
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- 2-alkylidene-aminoguanidines and methods of use therefor
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The present invention relates to compositions and methods for inhibiting nonenzymatic cross-linking (protein aging) which contain 2-alkylidene aminoguanidines and derivatives thereof. Accordingly, a composition is disclosed which comprises an agent capable of inhibiting the formation of advanced glycosylation endproducts of target proteins by reacting with the carbonyl moiety of the early glycosylation product of such target proteins formed by their initial glycosylation. The method comprises contacting the target protein with the composition. Both industrial and therapeutic applications for the invention are envisioned, as food spoilage and animal protein aging can be treated.
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- Kinetic study of the reaction of acetoacetate with glycine and sodium nitroprusside.
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This paper describes an extensive kinetic study of the reactions involved in the determination of acetoacetate in body fluids. It is concluded that acetoacetate reacts with glycine to produce an imine intermediate that tautomerizes to an enamine. It is also concluded that nitroprusside reacts with the imine intermediate to produce an unstable product with an absorption maximum near 540 nm. This product decays slowly to produce a stable product with an absorption maximum near 393 nm. A proposed reaction pathway is used to develop kinetic equations, rate constants, equilibrium constants, and molar absorptivity of the unstable product that permit quantitative prediction of the kinetic behavior for a wide range of reactant concentrations.
- Laios,Pardue
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p. 1903 - 1909
(2007/10/02)
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- Production of (S)-(+)-3-Hydroxybutyric Acid from 1,3-Butanediol by Resting Cells of Yeasts
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Various yeast strains were screened for production of 3-hydroxybutyric acid (3-HBA) from 1,3-butanediol (1,3-BD) by a resting cell system.Many yeasts were found to oxidize 1,3-BD to 3-HBA.Among them, Hansenula anomala IFO 0195 produced (S)-(+)-3-HBA of the highest optical purity and production of the acid.When resting cells of this strain were incubated at 27 deg C in an optimal reaction mixture containing 60.0 mg/ml 1,3-BD, 2.0percent CaCO3, and 1.0percent glucose, 26.7 mg/ml of 3-HBA were produced with 88percent enantiomer excess for 2 days.Dominant accumulation of (S)-(+)-3-HBA might be due to enantioselective degradation of (R)-(-)-3-HBA, though both (S)-(+)- and (R)-(-)-1,3-BD are oxidized by the strain.
- Shigeno, Toshiya,Katayama, Akiko,Nakahara, Tadaatsu
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p. 320 - 323
(2007/10/02)
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- 2-alkylidene-aminoguanidines and methods of use therefor
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The present invention relates to compositions and methods for inhibiting nonenzymatic cross-linking (protein aging) which contain 2-alkylidene aminoguanidines and derivatives thereof. Accordingly, a composition is disclosed which comprises an agent capable of inhibiting the formation of advanced glycosylation endproducts of target proteins by reacting with the carbonyl moiety of the early glycosylation product of such target proteins formed by their initial glycosylation. The method comprises contacting the target protein with the composition. Both industrial and therapeutic applications for the invention are envisioned, as food spoilage and animal protein aging can be treated.
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- The E1cb Route for Ester Hydrolysis; Volumes of Activation as an Additional Criterion of Mechanism
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Hydrolyses of esters which possess an acidic proton at the α or vinylogous position can, in principle, hydrolyse by the E1cb route via a ketenoid intermediate.To the kinetic evidence for such a mechanism in the hydrolyses of 4-hydroxybenzoates, malonates, acetoacetates and fluorenecarboxylates is now added the further criterion of volumes of activation.Values of ΔV(excit.) for reactions proceeding by the E1cb route are positive and contrast with the negative values associated with hydrolyses by the more usual BAc2 mechanism.
- Isaacs, Neil S.,Najem, Tariq S.
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p. 557 - 562
(2007/10/02)
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- ENZYMATIC REACTIONS IN ORGANIC SYNTHESIS 4- HYDROLYSES OF DIESTERS
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Enzymatic hydrolyses allowed discriminations of esters functions present in the same molecule.
- Jeso, B. De,Drouillard, S.,Degueil-Castaing, M.,Saux, A.,Maillard, B.
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p. 1691 - 1698
(2007/10/02)
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- Circulation-active substituted 1,4-dihydropyridine-3-carboxylic acid piperazides
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1,4-Dihydropyridine-3-carboxylic acid piperazides of the formula STR1 in which R1 is CN or alkyl, preferably methyl, R2 is H, CN, NO2 or preferably carboxyalkyl, R3 is aryl or heterocyclic, and R4 is alkyl, cycloalkyl, aryl or an acyl radical, and physiologically acceptable salts thereof, are circulation active. Novel intermediates are also provided.
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- Mutagen Formation on Photolysis of Dehydroacetic Acid
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Dehydroacetic acid (DHA) gave rise to some mutagenic substances on irradiation with ultraviolet (UV) light.Mutagenicity was detected toward Salmonella typhimurium TA 100 without the S-9 mix.A decrease in the absorbance maximum at 307 nm of DHA was accompanied by a simultaneous increase in total carbonyls and a slight decrease in pH.The mutagenicity of the substances derived from DHA was reduced by the addition of reducing agents, which suggested that the mutagenic substances might be carbonyl compounds.From the results of analysis of carbonyl compounds by GC-mass spectrometry and determination of their mutagenicities in the UV-irradiated DHA sample, it was confirmed that the mutagenicity of the sample was mainly due to 2-pentanal.
- Yamaguchi, Tsutomu
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p. 167 - 172
(2007/10/02)
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- Knoevenagel Reactions with β-Oxo Acids. Regiospecific Enol Equivalents for Syntheses of α,β-Unsaturated Ketones and of Some β-Ketols
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3-Oxobutanoic acid reacts with aliphatic aldehydes in the presence of pyridine to give α,β-unsaturated methyl ketones in good yields.Analogous results were obtained with a series of other β-oxo acids.Synthesis of (E)-7-methyloct-4-en-3-one, a major constituent of the marine sponge Plakortis zygompha, has been carried out using this methodology.Aromatic aldehydes are generally less reactive under these conditions but give β-ketols when the phenyl ring bears an electron-withdrawing substituent.Some observations on the mechanism of the reaction between 3-oxobutanoic acid and benzaldehyde are presented.
- Grayson, David H.,Tuite, Mathew R. J.
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p. 2137 - 2142
(2007/10/02)
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- ELECTROSYNTHESIS OF CARBOXYLIC ACIDS FROM ORGANIC HALIDES AND CARBON DIOXIDE
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The electrocarboxylation of a large variety of organic halides is achieved in simple and mild conditions in diaphragm-less cells.
- Sock, Oumar,Troupel, Michel,Perichon, Jacques
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p. 1509 - 1512
(2007/10/02)
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- Use of β-Ketocarboxylic Acids for Syntheses of 6-Substituted 4-Hydroxy-2-pyrones and Acyclic β-Diketones
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β-Ketocarboxylic acids including β-ketoglutaric acid half-esters were cyclized by treating them with 1,1'-carbonyl-diimidazole to give 6-substituted 3-acyl-4-hydroxy-2-pyrones in good yields. 5-Aryl-3,5-dioxo-1-pentanoic acid and monomethyl malonate gave 6-aryl-4-hydroxy-2-pyrone and dimethyl β-ketoglutarate, respectively, on similar treatment.Anibin, one of the Aniba alkaloids, was synthesized from 5-(3-pyridyl)-4-hydroxy-2-pyrone.In addition, it was confirmed that reaction of magnesium β-ketocarboxylate with acylimidazolide gave the corresponding acyclic β-diketone in excellent yield.Keywords - β-ketocarboxilic acid; biogenetic-type synthesis; 4-hydroxy-2-pyrone; β-polyketide; β-ketoglutaric acid; dehydroacetic acid; anibin; Aniba alkaloid; 3-acyl-4-hydroxy-2-pyrone; β-diketone.
- Ohta, Shunsaku,Tsujimura, Atsuhiko,Okamoto, Masao
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p. 2762 - 2768
(2007/10/02)
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- Leaving Group Effects in Thiolester Alkaline Hydrolysis. Part 1. A Keten-mediated (E1cB) Pathway for Basic Hydrolysis of S-Acetoacetylcoenzyme A and Analogues
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The basic hydrolysis of a series of leaving-group substituted acetothiolacetates (CH3COCH2COSR) has been studied in aqueous media.Hydrolysis of N-acetyl-S-acetoacetylcysteinamine follows a kinetic ionisation curve with an inflexion corresponding to the pK of this ester as determined by spectrophotometric and electrometric titrations.The rate constant at high pH was shown to follow a Broensted relationship with βL.G. -1.13, where βL.G. is the slope of a plot of the logarithm of the rate constant versus the pKa of the conjugate acid of the leaving group.This, and other evidence from rate comparisons, activation parameters, and kinetic solvent isotope effects, indicated an E1cB hydrolytic mechanism involving unimolecular collapse of the ester enolate ions via a ketenoid transition-state.S-Acetoacetylcoenzyme-A was also hydrolysed in base by this mechanism.Direct comparison of rates of leaving group expulsion for ArS and ArO was possible by means of this unimolecular process.For a leaving group with pKL.G. 10, the oxyanion departs ca. 1 or 2 orders of magnitude faster than the thiolate anion; for pKL.G. 6.0, the advantage of oxygen over sulphur is 103-104 fold.In a direct structural comparison, PhS departs 32 times as rapidly as PhO.The contribution of steric release in the E1cB transition-state for S-t-butyl acetothiolacetate hydrolysis is discussed.The pKa values of some acetothiolacetates were measured.
- Douglas, Kenneth T.,Yaggi, Norbert F.
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p. 1037 - 1044
(2007/10/02)
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- Process for carboxylating organic substrates with carbon dioxide in hydrocarbon solvents
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Carboxylable substrates i.e., ketones, esters, nitroparaffins and nitriles, containing activated hydrogen atoms are carboxylated by reaction with alkaline phenates and CO2 in at least one hydrocarbon solvent selected from aliphatic, alicyclic, aromatic and alkyl-aromatic hydrocarbon solvents.
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- Method for the production of haloacetoacetic acids
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Haloacetoacetic acids of the formula wherein R1 represents chlorine or bromine and R2 and R3 each represents hydrogen, chlorine or bromine, are obtained by converting diketene into a chloro or bromo acetoacetic acid halide by means of chlorine or bromine at a temperature of from about -10° to -40°C, and the acetoacetic chloro or bromoacetoacetic acid halide is converted into the corresponding acid by hydrolysis with a stoichiometrically equivalent (or excess) quantity of water.
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- Alkylidenedithiobisphenols
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Compounds having the general formula: EQU1 where R is an alkyl radical substituted by a radical selected from the class consisting of alkoxy, carbonyl and ester radicals. The compounds are useful for reducing blood cholesterol in warm-blooded animals.
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