- UV Photochemistry of Acetylacetaldehyde Trapped in Cryogenic Matrices
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The broad band UV photochemistry of acetylacetaldehyde, the hybrid form between malonaldehyde and acetylacetone (the two other most simple molecules exhibiting an intramolecular proton transfer), trapped in four cryogenic matrices, neon, nitrogen, argon, and xenon, has been studied by IRTF spectroscopy. These experimental results have been supported by B3LYP/6-311G++(2d,2p) calculations in order to get S0 minima together with their harmonic frequencies. On those minima, we have also calculated their vibrationally resolved UV absorption spectra at the time-dependent DFT ωB97XD/6-311++G(2d,2p) level. After deposition, only the two chelated forms are observed while they isomerize upon UV irradiation toward nonchelated species. From UV irradiation effects we have identified several nonchelated isomers, capable, in turn, of isomerizing and fragmenting, even if this last phenomenon seems to be most unlikely due to cryogenic cages confinement. On the basis of these findings, we have attempted a first approach to the reaction path of electronic relaxation. It appeared that, as with acetylacetone, the path of electronic relaxation seems to involve triplet states.
- Coussan, S.,Ferré, N.,Rousselot-Pailley, P.,Sobanska, S.
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- Straightforward entry into 5-hydroxy-1-aminopyrrolines and the corresponding pyrroles from 1,2-diaza-1,3-butadienes
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The synthesis of 5-hydroxy-1-aminopyrroline-3-carboxylic acid derivatives and 5-unsubstituted-1-aminopyrrole-3-carboxylic acid derivatives from 1,2-diaza-1,3-butadienes and aldehydes is presented. These domino reactions offer the advantage of executing multistep transformation without intermediate workup procedures. The stereoselectivity of ring closure to 5-hydroxy-1-aminopyrroline-3-carboxylic acid derivatives and phenyl transposition to 2,3-diphenyl-1-aminopyrrole-3-carboxylic acid derivatives are also studied.
- Attanasi, Orazio A.,De Crescentini, Lucia,Favi, Gianfranco,Filippone, Paolino,Mantellini, Fabio,Santeusanio, Stefania
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- Cassis and Green Tea: Spontaneous Release of Natural Aroma Compounds from β-Alkylthioalkanones
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In depth headspace analysis of the slow degradation of β-alkylthioalkanones in ambient air led to the discovery of a novel δ-cleavage pathway, by which β-mercaptoketones are released. Since β-mercaptoketones are potent natural aroma compounds occurring in many fruits, herbs and flowers, the discovery of an enzyme-independent molecular precursor for this class of high-impact molecules is of practical importance. Moreover, the formation of β-diketones and aldehydes by concomitant oxidation at the α-sulfur-position enhances the versatility of this class of aroma precursors. A mechanistic model is proposed which suggests that the oxidative degradation occurs through a novel Pummerer-type rearrangement of initially formed persulfoxides.
- B?ttig, Sarah,Bochet, Christian G.,Egger, Timothy,Flachsmann, Felix,Gey, Olga
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- Reaction of alkyl- and arylamines with 2-(hydroxyimino)-3-oxobutanal
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The condensation of 2-(hydroxyimino)-3-oxobutanal with primary aliphatic amines, cyclohexanamine, and amines containing an adamantane fragment afforded 4-(alkylamino)- and 4-(cyclohexylamino)-3- nitrosobut-3-en-2-ones. Analogous reaction with substituted anilines RC6H4NH2 (R = H, 4-Me, 4-OMe, 4-NH2, 4-Br, 4-I, 3-NO2) led to the formation of 4-aryl-3-hydroxyiminobutan-2-ones.
- Yarofeeva,Tsutsura,Frolenko,Semichenko,Kondrasenko,Suboch
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- SUBSTITUTED PYRROLO[1,2-A]PYRIMIDINES AND THEIR USE IN THE TREATMENT OF MEDICAL DISORDERS
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The invention provides substituted pyrrolo[l,2-a]pyrimi dines and related organic compounds, compositions containing such compounds, medical kits, and methods for using such compounds and compositions to treat medical disorders, e.g., Gaucher disease, Parkinson's disease, Lewy body disease, dementia, or multiple system atrophy, in a patient. Exemplary substituted pyrrolo[1,2-a]pyrimidines compounds described herein include substituted 2,4-dimethyl-N-phenylpyrrolo[l,2-a]pyrimidine-8-carboxamide compounds and variants thereof.
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Paragraph 00547
(2016/06/28)
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- Thiamine pyrophosphate stimulates acetone activation by desulfococcus biacutus as monitored by a fluorogenic ATP analogue
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Acetone can be degraded by aerobic and anaerobic microorganisms. Studies with the strictly anaerobic sulfate-reducing bacterium Desulfococcus biacutus indicate that acetone degradation by these bacteria starts with an ATP-dependent carbonylation reaction leading to acetoacetaldehyde as the first reaction product. The reaction represents the second example of a carbonylation reaction in the biochemistry of strictly anaerobic bacteria, but the exact mechanism and dependence on cofactors are still unclear. Here, we use a novel fluorogenic ATP analogue to investigate its mechanism. We find that thiamine pyrophosphate is a cofactor of this ATP-dependent reaction. The products of ATP cleavage are AMP and pyrophosphate, providing first insights into the reaction mechanism by indicating that the reaction proceeds without intermediate formation of acetone enol phosphate.
- Gutiérrez Acosta, Olga B.,Hardt, Norman,Hacker, Stephan M.,Strittmatter, Tobias,Schink, Bernhard,Marx, Andreas
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p. 1263 - 1266
(2014/07/08)
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- Branching ratios for the reaction of selected carbonyl-containing peroxy radicals with hydroperoxy radicals
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An important chemical sink for organic peroxy radicals (RO2) in the troposphere is reaction with hydroperoxy radicals (HO2). Although this reaction is typically assumed to form hydroperoxides as the major products (R1a), acetyl peroxy radicals and acetonyl peroxy radicals have been shown to undergo other reactions (R1b) and (R1c) with substantial branching ratios: RO2 + HO2 → ROOH + O2 (R1a), RO 2 + HO2 → ROH + O3 (R1b), RO2 + HO2 → RO + OH + O2 (R1c). Theoretical work suggests that reactions (R1b) and (R1c) may be a general feature of acyl peroxy and α-carbonyl peroxy radicals. In this work, branching ratios for R1a-R1c were derived for six carbonyl-containing peroxy radicals: C2H 5C(O)O2, C3H7C(O)O2, CH3C(O)CH2O2, CH3C(O)CH(O 2)CH3, CH2ClCH(O2)C(O)CH 3, and CH2ClC(CH3)(O2)CHO. Branching ratios for reactions of Cl-atoms with butanal, butanone, methacrolein, and methyl vinyl ketone were also measured as a part of this work. Product yields were determined using a combination of long path Fourier transform infrared spectroscopy, high performance liquid chromatography with fluorescence detection, gas chromatography with flame ionization detection, and gas chromatography-mass spectrometry. The following branching ratios were determined: C2H5C(O)O2, YR1a = 0.35 ± 0.1, YR1b = 0.25 ± 0.1, and YR1c = 0.4 ± 0.1; C3H7C(O)O2, YR1a = 0.24 ± 0.15, YR1b = 0.29 ± 0.1, and YR1c = 0.47 ± 0.15; CH3C(O)CH2O2, Y R1a = 0.75 ± 0.13, YR1b = 0, and YR1c = 0.25 ± 0.13; CH3C(O)CH(O2)CH3, Y R1a = 0.42 ± 0.1, YR1b = 0, and YR1c = 0.58 ± 0.1; CH2ClC(CH3)(O2)CHO, Y R1a = 0.2 ± 0.2, YR1b = 0, and YR1c = 0.8 ± 0.2; and CH2ClCH(O2)C(O)CH3, YR1a = 0.2 ± 0.1, YR1b = 0, and YR1c = 0.8 ± 0.2. The results give insights into possible mechanisms for cycling of OH radicals in the atmosphere.
- Hasson, Alam S.,Tyndall, Geoffrey S.,Orlando, John J.,Singh, Sukhdeep,Hernandez, Samuel Q.,Campbell, Sean,Ibarra, Yesenia
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experimental part
p. 6264 - 6281
(2012/08/28)
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- Modular synthesis of phenanthridine derivatives by oxidative cyclization of 2-isocyanobiphenyls with organoboron reagents
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Where HAS you been? A manganese-mediated annulation of 2-isocyanobiaryls with organoboronic acids is developed for the synthesis of a broad range of phenanthridine derivatives (see scheme). Mechanistic studies indicate that the reaction proceeds by the intramolecular homolytic aromatic substitution (HAS) of an imidoyl radical intermediate. Copyright
- Tobisu, Mamoru,Koh, Keika,Furukawa, Takayuki,Chatani, Naoto
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supporting information
p. 11363 - 11366
(2013/01/15)
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- Transformations of dialkyl(4-hydroxy-2-butynyl)-(3-phenylallyl)ammonium bromides in an KOH aqueous solution or in the presence of powdered KOH
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Under the action of a twofold excess of KOH and heating in aqueous solution, and also under the conditions of the Stevens rearrangement (with KOH powder and a small amount of methanol) dialkyl-(4-hydroxy-2-butynyl)(3- phenylallyl)ammonium bromides form dialkyl[4-(1-phenylallyl)-2,5-dihydro-2- furyl]amines. Rearrangement-cleavage reaction also occurs under the same conditions.
- Chukhadjian,Gabrielyan,Chukhadjian,Shahkhatuni,Panosyan
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experimental part
p. 418 - 424
(2012/01/13)
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- The gas-phase ozonolysis of α-humulene
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α-Humulene contains three double bonds (DB), and after ozonolysis of the first DB the first-generation products are still reactive towards O 3 and produce second- and third-generation products. The primary aim of this study consisted of identifying the products of the three generations, focusing on the carboxylic acids, which are known to have a high aerosol formation potential. The experiments were performed in a 570 litre spherical glass reactor at 295 K and 730 Torr. Initial mixing ratios were 260-2090 ppb for O3 and 250-600 ppb for α-humulene in synthetic air. Reactants and gas-phase products were measured by in situ FTIR spectroscopy. Particulate products were sampled on Teflon filters, extracted with methanol and analyzed by LC-MS/MS-TOF. Using cyclohexane (10-100 ppm) as an OH-radical scavenger and by monitoring the yield of cyclohexanone by PTR-MS, an OH-yield of (10.5 ± 0.7)% was determined for the ozonolysis of the first DB, and (12.9 ± 0.7)% of the first-generation products. The rate constant of the reaction of O3 with α-humulene is known as k0 = 1.17 × 10-14 cm3 molecule-1 s-1 [Y. Shu and R. Atkinson, Int. J. Chem. Kinet., 1994, 26, 1193-1205]. The reaction rate constants of O3 with the first-generation products and the second-generation products were, respectively, determined as k1 = (3.6 ± 0.9) × 10-16 and k2 = (3.0 ± 0.7) × 10-17 cm3 molecule-1 s -1 by Facsimile-simulation of the observed ozone decay by FTIR. A total of 37 compounds in the aerosol phase and 5 products in the gas phase were tentatively identified: 25 compounds of the first-generation products contained C13-C15 species, 9 compounds of the second-generation products contained C8-C11 species, whereas 8 compounds of the third-generation products contained C4-C6 species. The products of all three generations consisted of a variety of dicarboxylic-, hydroxy-oxocarboxylic- and oxo-carboxylic acids. The formation mechanisms of some of the products are discussed. The residual FTIR spectra indicate the formation of secondary ozonides (SOZ) in the gas phase, which are formed by the intramolecular reaction of the Criegee moiety with the carbonyl endgroup. These SOZ revealed to be stable over several hours and its formation was shown not to be affected by the addition of Criegee-radical scavengers such as HCOOH or H2O. This suggests that in the ozonolysis of α-humulene at atmospheric pressures the POZ will decompose rapidly, and that a large fraction of the formed exited Criegee Intermediate will be stabilized to form stable SOZ, while the formation of OH-radicals via the hydroperoxide channel will be a minor process. the Owner Societies.
- Beck,Winterhalter,Herrmann,Moortgat
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experimental part
p. 10970 - 11001
(2012/01/02)
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- Stereoselective control in the Staudinger reactions involving monosubstituted ketenes with electron acceptor substituents: Experimental investigation and theoretical rationalization
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The stereoselectivity of the Staudinger reactions involving monosubstituted ketenes with electron acceptor substituents was investigated experimentally by determination of the product stereochemistry and theoretically via DFT calculations. The results indicate that imines preferentially attack the less sterically hindered exo-side of the ketenes to generate zwitterionic intermediates. Subsequently, for cyclic imines, the intermediates undergo a conrotatory ring closure directly to produce β-lactams, while for linear imines, the imine moiety of the intermediates isomerizes to more stable intermediates, which further undergo a conrotatory ring closure to afford trans-β-lactams. The steric hindrance and the isomerization, rather than the torquoelectronic effect, play crucial roles in controlling the stereoselectivity in the practical Staudinger reactions involving monosubstituted ketenes with electron acceptor substituents, although the unaccessible borylketene with a powerful electron acceptor group controls the stereoselectivity torquoelectronically, in theory.
- Qi, Hengzhen,Li, Xinyao,Xu, Jiaxi
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supporting information; experimental part
p. 2702 - 2714
(2011/05/19)
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- Expeditious synthesis of 2,3,6-trisubstituted 2 H -1,3-oxazin-4(3 H)-ones via the tertiary amine-induced reaction of 2-diazo-3-oxoalkanals and imines under mild conditions
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A series of 2,3,6-trisubstituted 2H-1,3-oxazin-4(3H)-one derivatives were conveniently synthesized in satisfactory to good yields by the reaction of imines with 2-diazo-3-oxoalkanals in the presence of a catalytic amount of a tertiary amine during several seconds under mild condition. Different bases and -diazo - dicarbonyl compounds were also evaluated and a reaction mechanism is proposed. Compared with the corresponding thermal- and photo-induced- reactions, the current method is a metal-free, mild, highly regioselective, and more efficient approach for the synthesis of 2H-1,3-oxazin-4(3H)-one derivatives. Georg Thieme Verlag Stuttgart - New York.
- Qi, Hengzhen,Zhang, Jiantao,Xu, Jiaxi
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supporting information; experimental part
p. 887 - 894
(2011/05/05)
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- Synthesis of the naphthalenone, dihydroquinoline, and dihydrofuran derivatives
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The reactions of enaminones with dimethyl diazomalonate were investigated in the presence of copper(II) acetylacetonate. From the reaction of (E)-3-[methyl(phenyl)amino]-1-phenylprop-2-en-1-one (6c), dimethyl 2-[methyl(phenyl)amino]-4-oxonaphthalene-1,1-(4H)-dicarboxylate, was unexpectedly obtained as the major product. Quinoline derivatives were formed as the major products in the case of N-methyl-p-anisidino and N-methyl-p-toluidino enaminones. The reactions of acetyl enaminones were also realized, and quinoline derivatives were isolated as the major products. 3H- and 5H-dihydrofurans were also formed as side products in these reactions. These results differ from those reported earlier on the reactions of tertiary enaminones with carbenes/metal carbenes.
- Guengoer, Fuesun Seyma,Anac, Olcay,Sezer, Oezkan
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experimental part
p. 1115 - 1129
(2011/08/05)
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- Gas-phase pyrolysis of N-alkoxyphthalimides to functionally substituted aldehydes: Kinetic and mechanistic study
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Flash vacuum Pyrolysis (FVP) of primary N-alkoxyphthalimides at 400-500 C° and 0.02 Torr gave functionally substituted aldehydes. A mechanism of this pyrolytic transformation was proposed based on the kinetic data and product analysis. ARKAT USA, Inc.
- Al-Etaibi, Alya M.,Al-Awadi, Nouria A.,Ibrahim, Maher R.,Ibrahim, Yehia A.
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experimental part
p. 149 - 162
(2010/12/25)
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- Method for preparing chiral diphosphines
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The invention concerns a method for preparing a compound of formula (1) wherein: A represents naphthyl or phenyl optionally substituted; and Ar1, Ar2independently represent a saturated or aromatic carbocyclic group, optionally substituted.
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- Asymmetric hydrogenation method of a ketonic compound and derivative
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The present invention relates to a process for the asymmetric hydrogenation of a ketonic compound and derivative. The invention relates to the use of optically active metal complexes as catalysts for the asymmetric hydrogenation of a ketonic compound and derivative. The process for the asymmetric hydrogenation of a ketonic compound and derivative is characterized in that the asymmetric hydrogenation of said compound is carried out in the presence of an effective amount of a metal complex comprising as ligand an optically active diphosphine corresponding to one of the following formulae: STR1
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- Construction of Hydroxylated Alkaloids (+/-)-Mannonolactam, (+/-)-Deoxymannojirimycin, and (+/-)-Prosopinine through Aza-Annulation
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The aza-annulation of β-enamino carbonyl substrates with acrylate derivatives provides an efficient and convenient route for the regioselective construction of δ-lactams.This two-step ring-forming sequence involved initial generation of the benzyl enamine through either a condensation or conjugate addition reaction with BnNH2, followed by aza-annulation with acryloyl chloride or acrylic anhydride.Controlled by the rigid framework of the intermediate lactam, introduction of ring substituents was accomplished with high relative stereoselectivity.The carbonyl functionality, which was necessary to direct the regioselectivity of the aza-annulation reaction, was then transformed into a protected hydroxyl substituent through Baeyer-Villiger oxidation.The resultant δ-lactam product was used as a valuable intermediate in the synthesis of three natural products.Subsequent modification of this δ-lactam gave the naturally occurring α-mannosidase inhibitors (+/-)-mannonolactam and (+/-)-deoxymannojirimycin, while synthesis of the alkaloid (+/-)-prosopinine was accomplished through homologation of the lactam carbonyl.
- Cook, Gregory R.,Beholz, Lars G.,Stille, John R.
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p. 3575 - 3584
(2007/10/02)
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- An Experimental Study of the Reactions CH3CHO + Cl, C2H4O + Cl, and C2H4O + F in the Gas-Phase
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The reactions of chlorine and fluorine atoms with the structural isomers CH3CHO and C2H4O have been studied at low pressures and room temperature by the discharge flow technique with mass spectrometric detection.Using the reference reactions C2H6 + Cl --> C2H5 + HCl (0) C2H6 + F --> C2H5 + HF (00) the relative rate constant for the reactions CH3CHO + Cl --> products (1) C2H4O + Cl --> products (2) C2H4O + F --> products (3) were determined: k1/k0 = 1.04 +/- 0.09, k2/k0 = 0.49 +/- 0.04, k3/k00 = 0.47 +/- 0.05. - Reaction (1) proceeds mainly via hydrogen abstraction from the aldehyde group (>93percent) forming CH3CO.In the reactions of ethylene oxide (2), (3) the abstraction route is observed, contributions from addition channels in reaction (2) are discussed. - Keywords: Chemical Kinetics / Elementary Reactions / Mass Spectrometry / Radicals
- Bartels, M.,Hoyermann, K.,Lange, U.
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p. 423 - 427
(2007/10/02)
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- Obtention d'aldehydes γ-fonctionnels au cours de la thermolyse du percarbonate de O,O-t-butyle et O-vinyle en solution
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Owing to its peroxyester group, O,O-tert-butyl and O-vinyle peroxycarbonate may act as a free radical initiator in solution, but also, due to the presence of the vinylic insaturation, as a substrate for free radical addition reactions. - In such solvents as cumene which give free radicals unable to add to the double bond, the peroxycarbonate merely behaves as a vinyloxy radicals generator.It is thus possible to observe these radicals reacting either as formylmethyl radicals or as acetyl radicals. - In solvents such as cyclohexane which give free radicals able to add to the double bond, the reaction results in the substitution of formylmethyl groups to labile hydrogens of the solvent. - By applying the reaction to such compounds as ketones, ethers, acids and their derivatives, we could obtain γ-functional aldehydes (γ-ketoaldehydes, γ-oxaaldehydes and derivatives of succinaldehydic acids).These products are often difficult to prepare by other routes and until now only some of them have been described.
- Filliatre, Claude,Villenave, Jean-Jacques,Jaouhari, Rabih,Baratchart, Michel
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p. 352 - 356
(2007/10/02)
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- THE TWO STAGES OF THE ACID-CATALYZED HYDRATION OF 1-ALKOXY-1-BUTEN-3-YNES AND THE EFFECT OF CIS-TRANS ISOMERISM
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The kinetics of the acid-catalyzed hydrolysis of alkoxybutenynes under mild conditions were studied, and this made it possible to measure the rate of the first stage of the reaction.It was shown that the reaction rate depends on the configuration of the initial alkoxybutenynes.
- Vavilova, A. N.,Trofimov, B. A.,Volkov, A. N.,Keiko, V. V.
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p. 809 - 812
(2007/10/02)
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