- A Convenient Preparation of Ethyl Vinyl Ketone
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A four-step synthesis of ethyl vinyl ketone conveniently gives 67percent overall yield.
- Byrne, Brian,Wengenroth, Karl J.
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- Products and mechanism of the reaction of chlorine atoms with 3-pentanone in 700-950 Torr of N2/O2 diluent at 297-515 K
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The products, kinetics, and mechanism of the reaction Cl + 3-pentanone have been measured by UV irradiation of Cl2/3-pentanone/N2 (O2) mixtures using primarily GC analysis with selected cross checks by FTIR. In the absence of O2, the products are 1- and 2-chloro-3-pentanone with yields of 21 and 78%, respectively. As the temperature is increased, the yield of 1-chloro-3-pentanone increases modestly relative to the 2-chloro-3-pentanone yield. On the basis of this increase, the activation energy for hydrogen abstraction at the 1 position is determined to be 500 (±500) cal mole-1 relative to abstraction at the 2 position. In the presence of 500 ppm of O2 with 900-1000 ppm of Cl2 at 297 K, the yield of 2-chloro- 3-pentanone decreases dramatically from 78 to 2.5%, while the 1-chloro-3-pentanone decreases only modestly from 21 to 17%. The observed oxygenated species are acetaldehyde (59%), 2,3-pentanedione (9%), and propionyl chloride (56%). Increasing the temperature to 420 K (O2 = 500 ppm) suppresses these oxygenated products, and 2-chloro-3-pentanone again becomes the primary product, indicating that the O2 addition reaction to the 2-pentanonyl radical has become reversible. At 500 K and 10 000 ppm O 2, a new product channel opens which forms a small yield (～4%) of ethylvinylketone. Computer modeling of the product yields has been performed to gain an understanding of the overall reaction mechanism in the presence and absence of O2. The reaction of chlorine atoms with 3-pentanone proceeds with a rate constant of 8.1 (±0.8) × 10-11 cm3 molecule-1 s-1 independent of temperature over the range of 297-490 K (Ea = 0 ± 200 cal mole-1). Rate constant ratios of K(C2H 5C(O)CHCH3 + Cl2)/ k(C2H 5C(O)CHCH3 + O2) = 0.0185 ± 0.0037 and k(C2H5C(O)CH2CH + Cl2)/ k(C 2H5CH2C(O)CH2CH2 + O 2) = 2.7 ± 0.4 were determined at 297 K in 800-950 Torr of N2/O2 diluent. In 800-950 Torr of N2/O 2 diluent, the major fate of the alkoxy radical CH 3CH(O)C(O)C2H5 is decomposition to give C 2H5C(O) radicals and CH3CHO. These results show that the chemical mechanisms of the 3-pentanone reactions are very similar to those observed for butanone. In addition, the rate constants of the reactions of chlorine atoms with 1-chloro-3-pentanone [3 (±0.6) x 10-11 over the range of 297-460 K], 2,3-pentanedione [1.4 (±0.3) × 10-11 at 297 K], and ethylvinylketone [1.9 (±0.4) × 10-10 over the range of 297-400 K, decreasing rapidly above 400 K] were measured at ambient pressure.
- Kaiser,Wallington,Hurley
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- Methylvinyl Ketone Formation over Synthetic Chrysotile
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Selective formation of methylvinyl ketone (MVK) was attained over chrysotile, Mg3(OH)4Si2O5, through aldol condensation reaction between acetone and formaldehyde, the selectivity being 98 percent on both acetone and formaldehyde bases.Synthetic Co2+-substituted chrysotile, CoxMg3-x(OH)4Si2O5 (x= 0.15 or 0.9), catalyzed the reaction between acetone and methanol to give MVK and methylethyl ketone (MEK) with 75 percent selectivity on acetone basis.
- Suzuki, Eiichi,Idemura, Satoshi,Ono, Yoshio
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- The dual role of cis-[RuCl2(dmso)4] in the synthesis of new water-soluble Ru(II)-phosphane complexes and in the catalysis of redox isomerization of allylic alcohols in aqueous-organic biphasic systems
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New air-stable, water-soluble Ru(II)-phosphane complexes were synthesized in high purity by the reaction of cis-[RuCl2(dmso)4] with 2 equivalents of 1,3,5-triaza-7-phosphaadamantane (pta) and its N-methyl and N-benzyl derivatives (pta-Me and pta-Bn, respectively). All new complexes were characterized by elementary analysis and spectroscopic methods (NMR, ESI-MS) and the molecular structures of cis-cis-trans-[RuCl2(dmso) 2(pta)2], cis-cis-trans-[RuCl2(dmso) 2(pta-H)2]Cl2 (obtained in acidic solutions) and that of cis-cis-trans-[RuCl2(dmso)2(pta-Me) 2](CF3SO3)2 were determined by single crystal X-ray diffraction. Under mild conditions, cis-[RuCl 2(dmso)4] actively catalyzed the transformation of allylic alcohols into the corresponding ketones with 100% selectivity while in the same reaction the new Ru(II)-pta complexes showed moderate activity and selectivity.
- Udvardy, Antal,Bényei, Attila Csaba,Kathó, ágnes
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- Cu2O-CuO/Chitosan Composites as Heterogeneous Catalysts for Benzylic C?H Oxidation at Room Temperature
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Recently, in catalysis, chitosan has been exploited as a macrochelating ligand for metal active species due to the presence of various functional groups in its structure. Moreover, copper-based catalysts are classified as one of the most environmentally friendly catalytic systems and their use for the oxidation of alkylarene has not been established much. Therefore, in this work, the hydrothermal synthesis of copper oxide-chitosan composites as heterogeneous catalysts for the benzylic C?H oxidation of alkylarene was investigated. Characterization results reveal mixed phases of CuO and Cu2O, inferring the ability of chitosan to act as a reducing sugar under the hydrothermal condition. The pre-existing interaction between copper species and chitosan as well as the co-existence of the Cu2O and CuO structures give rise to the efficient performance of the catalysts. The synthesized composites exhibit high activity for the oxidation of fluorene to 9-fluorenone at room temperature and small catalyst loading (1 mol % of Cu, >90 % conversion and 100 % selectivity). Superior TOF was observed, and a good scope of substrates can be converted to corresponding ketones in 48–97 % yields with these copper oxide-chitosan catalysts. In addition, the catalysts can be used for up to nine cycles without significant decrease of the activity.
- Kanarat, Jurin,Bunchuay, Thanthapatra,Klysubun, Wantana,Tantirungrotechai, Jonggol
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p. 4833 - 4840
(2021/10/07)
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- Palladium mediated one-pot synthesis of 3-aryl-cyclohexenones and 1,5-diketones from allyl alcohols and aryl ketones
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One-pot synthesis of Robinson annulated 3-aryl-cyclohexenones from allyl alcohols and ketones using palladium is reported. Long chain aliphatic or aryl substitutions at the C1 position of allyl alcohol result in the formation of 1,5-diketone products. This simple one-pot method avoids the use of highly electrophilic vinyl ketones.
- Samser, Shaikh,Biswal, Priyabrata,Meher, Sushanta Kumar,Venkatasubbaiah, Krishnan
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supporting information
p. 1386 - 1394
(2021/02/27)
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- K2S2O8-promoted C-Se bond formation to construct α-phenylseleno carbonyl compounds and α,β-unsaturated carbonyl compounds
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A novel K2S2O8-promoted C-Se bond formation from cross-coupling under neutral conditions has been developed. A variety of aldehydes and ketones react well using K2S2O8 as the oxidant in the absence of catalyst and afford desired products in moderate to excellent yields. This protocol provides a very simple route for the synthesis of α-phenylseleno carbonyl compounds and α,β-unsaturated carbonyl compounds.
- Yang, Xue-Yan,Wang, Ruizhe,Wang, Lu,Li, Jianjun,Mao, Shuai,Zhang, San-Qi,Chen, Nanzheng
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p. 28902 - 28905
(2020/08/25)
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- Changes in the Key Odorants and Aroma Profiles of Hamlin and Valencia Orange Juices Not from Concentrate (NFC) during Chilled Storage
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Application of the aroma extract dilution analysis (AEDA) on the volatiles isolated by extraction/SAFE distillation from NFC (not from concentrate) juice from Hamlin oranges revealed 51 odor-active constituents in the flavor dilution (FD) factor range of 8 to 8192 among which vanillin, wine lactone, and (R)-linalool appeared with the highest FD factors. The AEDA applied on the volatile fraction of the same batch of juice stored at 0 °C for 10 months under aseptic conditions showed clear changes in the aroma profile as well as in the FD factors of key odorants. The reduction in the intensity of the citrus-like, pungent, green odor attributes in the aroma profile correlated with the loss of 1-penten-3-one, acetaldehyde, and (Z)-3-hexenal and a clear decrease in hexanal, octanal, nonanal, decanal, and (E,E)-2,4-decadienal. Quantitation done by stabile isotope dilution assays followed by a calculation of odor activity values (ratio of concentration to odor thresholds in citrate buffer) confirmed that the quick loss of 1-penten-3-one and acetaldehyde already within a few weeks and a significant reduction in nearly all aldehydes over the storage time of 10 months were responsible for the changes in the overall aroma profile of the juice. The same approach applied on Hamlin juice from the next harvest year as well as on chilled stored NFC juice from Valencia oranges confirmed the results for another harvest year and another orange variety.
- Sellami, Ines,Mall, Veronika,Schieberle, Peter
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p. 7428 - 7440
(2018/06/19)
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- Stereoselective Allylic Alkylation of 1-Pyrroline-5-carboxylic Esters via a Pd/Cu Dual Catalysis
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The asymmetric allylation of 1-pyrroline-5-carboxylic esters has been accomplished through a synergistic Pd/Cu catalyst system under mild reaction conditions. The mechanistic studies suggested that (1) nucleophilic attack is the enantiodiscriminating step; (2) the cooperative action of two chiral reactive species, N-metalated azomethine ylides and ?€-allylpalladium, is most likely responsible for its high reactivity and excellent enantioselectivity (up to >99% ee); and (3) the steric hindrance and electronic factors of the allylic electrophiles and imino ester substrates are crucial for the formation of the linear products. A series of 3,4-2H-pyrrole derivatives bearing a quaternary stereogenic center were easily synthesized in high yields and with high to excellent regioselectivity and enantioselectivity.
- Liu, Penglin,Huo, Xiaohong,Li, Bowen,He, Rui,Zhang, Jiacheng,Wang, Tianhong,Xie, Fang,Zhang, Wanbin
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supporting information
p. 6564 - 6568
(2018/10/20)
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- Expanding the scope of the Babler–Dauben oxidation: 1,3-oxidative transposition of secondary allylic alcohols
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We report the catalytic chromium-mediated oxidation of secondary allylic alcohols to give α,β-unsaturated aldehydes with exclusive (E)-stereoselectivity. This facile procedure employs catalytic PCC (5?mol?%) and periodic acid (H5IO6) as a co-oxidant. This transformation occurs specifically with aromatic substituted allyl alcohols containing both electron withdrawing and electron donating substituents as well as a range of functional groups.
- Killoran, Patrick M.,Rossington, Steven B.,Wilkinson, James A.,Hadfield, John A.
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supporting information
p. 3954 - 3957
(2016/08/09)
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- Morita-Baylis-Hillman Reaction of α,β-Unsaturated Ketones with Allylic Acetates by the Combination of Transition-Metal Catalysis and Organomediation
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An intermolecular Morita-Baylis-Hillman (MBH) reaction of α,β-unsaturated ketones with allylic acetates under the catalysis of 10 mol % of tetrakis(triphenylphosphine)palladium(0) and mediation of tributylphosphine has been developed in the presence of acetic acid, affording the desired α-coupling products. The MBH reaction has the advantages of good tolerance to many functional groups, excellent regioselectivity and E-stereoselectivity, and moderate to good yields.
- Li, Ya-Qiong,Wang, Hai-Jun,Huang, Zhi-Zhen
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p. 4429 - 4433
(2016/07/06)
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- 1H-pyrrole-2,4-dicarbonyl-derivatives and their use as flavoring agents
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The present invention primarily relates to 1H-pyrrole-2,4-dicarbonyl-derivatives of Formula (I) wherein R1, R2, R3, Z. Z' and J are as defined in the description, to mixtures thereof and to the use thereof as flavoring agents. The compounds in accordance with the present invention are suitable for producing, imparting, or intensifying an umami flavor. The invention further relates to flavoring mixtures, compositions for oral consumption as well as ready-to-eat, ready-to-use and semifinished products, comprising an effective amount of the compound of Formula (I) or of a mixture of compounds of Formula (I) and to specific methods for producing, imparting, modifying and/or intensifying specific flavor impressions.
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- Imidazo[1,2-a]pyridine-ylmethyl-derivatives and their use as flavoring agents
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The present invention primarily relates to imidazo[1,2-a]pyridine-ylmethyl-derivatives of Formula (I) wherein R1, R2, X, W e J are as defined in the description, to mixtures thereof and to the use thereof as flavoring agents. The compounds in accordance with the present invention are suitable for producing, imparting, or intensifying an umami flavor. The invention further relates to flavoring mixtures, compositions for oral consumption as well as ready-to-eat, ready-to-use and semifinished products, comprising an effective amount of the compound of Formula (I) and to specific methods for producing, imparting, modifying and/or intensifying specific flavor impressions.
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- 1,4-Diazabicyclo[2.2.2]octane-Promoted Aminotrifluoromethylthiolation of α,β-Unsaturated Carbonyl Compounds: N-Trifluoromethylthio-4-nitrophthalimide Acts as Both the Nitrogen and SCF3 Sources
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A novel difunctionalization reaction is described. It uses N-trifluoromethylthio-4-nitrophthalimide as the reagent, which serves as both the nitrogen and SCF3 sources. In the presence of DABCO (1,4-diazabicyclo[2.2.2]octane), the nitrogen and SCF3 groups can be incorporated into α,β-unsaturated carbonyl compounds easily and give versatile β-amino ketones and esters in good yields. This difunctionalization reaction features mild reaction conditions, high atom-economy, and efficient access to α-SCF3 amino acids.
- Xiao, Qing,He, Qijie,Li, Juncheng,Wang, Jun
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supporting information
p. 6090 - 6093
(2016/01/09)
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- Enantioselective synthesis of 3-substituted 1,2-oxazinanes via organocatalytic intramolecular aza-Michael addition
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A highly enantioselective intramolecular 6-exo-trig aza-Michael addition was developed to afford chiral 3-substituted 1,2-oxazinanes in high yields (up to 99% yield) and good enantioselectivities (up to 98/2 er). These reactions were enabled by a quinine-derived primary-tertiary diamine as a catalyst and pentafluoropropionic acid (PFP) as a co-catalyst.
- Cheng, Shuanghua,Yu, Shouyun
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supporting information
p. 8607 - 8610
(2014/12/10)
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- Oxygen as single oxidant for two steps: Base-free one-pot Pd(ii)-catalyzed alcohol oxidation & arylation to halogen-intact β-aryl α,β-enones
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Using oxygen as the sole oxidant for two steps, we developed a new method to synthesize β-aryl α,β-enones by fine-tuning the Pd(ii)-catalyzed oxidation of allyl alcohol to subsequent arylation with arylboronic acids, arylboronic ester and aryltrifluoroborate salt. This one-pot green method does not require copper salt, base, and intermediate isolation. Halogen-bearing chalcones, dibenzylideneacetones and arylalkyl enones were synthesized in good yields. This journal is
- Vellakkaran, Mari,Andappan, Murugaiah M. S.,Nagaiah, Kommu
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p. 45490 - 45494
(2014/12/10)
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- Acid-catalyzed reactions of epoxides for atmospheric nanoparticle growth
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Although new particle formation accounts for about 50% of the global aerosol production in the troposphere, the chemical species and mechanism responsible for the growth of freshly nucleated nanoparticles remain largely uncertain. Here we show large size
- Xu, Wen,Gomez-Hernandez, Mario,Guo, Song,Secrest, Jeremiah,Marrero-Ortiz, Wilmarie,Zhang, Annie L.,Zhang, Renyi
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supporting information
p. 15477 - 15480
(2015/02/18)
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- Synthesis of water-tolerant indium homoenolate in aqueous media and its application in the synthesis of 1,4-dicarbonyl compounds via palladium-catalyzed coupling with acid chloride
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The first water-tolerant, ketone-type indium homoenolate was synthesized via the oxidative addition of In/InCl3 to enones. The reaction proceeds exclusively in aqueous media. Both indium and indium(III) chloride are necessary for the smooth conversion of the reaction. Similar results were obtained when InCl or InCl2 was used in place of In/InCl3. The synthetic utility of the indium homoenolate was demonstrated through the synthesis of 1,4-dicarbonyl compounds via palladium-catalyzed coupling of indium homoenolate with acid chloride.
- Shen, Zhi-Liang,Goh, Kelvin Kau Kiat,Cheong, Hao-Lun,Wong, Colin Hong An,Lai, Yin-Chang,Yang, Yong-Sheng,Loh, Teck-Peng
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supporting information; experimental part
p. 15852 - 15855
(2011/01/10)
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- One single catalyst, Pd(OAc)2, for two sequential very different steps: Allylic alcohol oxidation-Heck reaction. Access to functionalised α,β-unsaturated ketones
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A single addition of the catalyst, Pd(OAc)2, was realised to mediate two transformations as different as allylic alcohol oxidation under O2 and C-C bond formation of the Heck type, to give substituted α,β-unsaturated ketones without intermediate purification. The Royal Society of Chemistry.
- Batt, Frederic,Gozzi, Christel,Fache, Fabienne
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supporting information; experimental part
p. 5830 - 5832
(2009/04/13)
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- Synthesis and pyrolytic and kinetic behaviour of β,δ′-dioxo-stabilised phosphorus ylides: Convenient preparation of γ,δ-alkynyl ketones and 2,3-functionalised butadienes
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Both ketone- and ester-stabilised phosphorus ylides undergo Michael addition to vinyl ketones to give the β,δ′-dioxo ylides 3 and 5, respectively, although in the latter case careful temperature control is required to avoid an undesired side-reaction. Under conditions of flash vacuum pyrolysis at 650 °C the ylides 3 generally undergo Ph3PO extrusion to afford the γ,δ-alkynyl ketones 14, although these are found to partly undergo a secondary fragmentation. In contrast, the ylides 5 react under the same conditions to give the synthetically useful 1,3-dienes 20 by way of cyclobutenes. Rate constants for the reaction of selected ylides 3 and 5 are reported. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).
- Aitken, R. Alan,Al-Awadi, Nouria A.,Balkovich, Mark E.,Bestmann, Hans Juergen,Clem, Oliver,Gibson, Scott,Gross, Andreas,Kumar, Ajith,Roeder, Thomas
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p. 840 - 847
(2007/10/03)
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- Porphyrins with exocyclic rings. Part 12. Synthesis of meso,β-butano- and meso,β-pentanoporphyrins from cycloalka[b]pyrroles
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Pyrroles 5 with b-face fused seven- or eight-membered carbocyclic rings were prepared in good yields by Knorr-type condensations with cycloheptanone or cyclooctanone, respectively. Treatment with lead tetraacetate in dichloromethane afforded the labile ω-acetates 8 and subsequent acid catalyzed condensation with α-unsubstituted pyrrole-2-carboxylates yielded the related pyrrolylcycloalka[b]pyrroles 29 and 30. The α-unsubstituted pyrroles 14 and 23 were prepared by condensing α,β-unsubstituted ketones, or their β-acetoxycarbonyl precursors, with benzyl N-tosylglycinate in the presence of DBU, followed by dehydration with POCl3-pyridine and base catalyzed elimination of p-toluenesulfinic acid. Dipyrrole dibenzyl esters 29 and 30 were hydrogenolysed over 10% Pd-C to give the corresponding dicarboxylic acids. Acid catalyzed condensation with diformyldipyrrylmethane 33 under modified MacDonald '2 + 2' conditions afforded a series of four cycloalkanoporphyrins 4a-d with seven- or eight-membered exocyclic rings. Although the meso,β-butanoporphyrins 4a and 4b were isolated in good yields, poorer results were obtained for the related meso,β-pentanoporphyrin: 4c and 4d. It is proposed that the eight-membered carbocyclic ring distorts the geometry of the open-chain tetrapyrrolic intermediates and this deleterious influence results in the lower yields observed.
- Bastian, Jolie A.,Lash, Timothy D.
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p. 6299 - 6310
(2007/10/03)
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- Palladium Catalyzed Alternating Cooligomerization of Ethylene and Carbon Monoxide to Unsaturated Ketones
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Cationic palladium catalysts have been used to cooligomerize ethylene and carbon monoxide.At high ethylene/CO ratios (m/m = 10:1) in methylene chloride as a solvent, unsaturated alternating cooligomers of the general structure RmH (m >/= 1; R = CH2=CH-, CH2=CHCH2CH2- and CH3CH=CHCH2-) were obtained for the first time.Single component catalyst precursors X)>(1+)Y(1-) (PX = Ph2P(CH2)nC(=O)OR, Ph2P(CH2)2P(=O)Ph2, , Ph2P(CH2)2S(=O)Ph, n = 1-3, R = Me, Et; Y(1-) = BF4(1-), SbF6(1-)) with bidentate P,O- and P,S-ligands as well as in situ catalysts with unfunctionalized phosphine ligands were used.With PnBu3 as a ligand, selectivities for ethylvinylketone of 40percent based on the CO converted were obtained.The hemilabile phosphino-ester and phosphino-thiophene ligands behave like monodentate phosphines under catalytic conditions. - Keywords: Cooligomerization, Carbonylation, Palladium, Hemilabile, Unsaturated Ketone
- Keim, Wilhelm,Maas, Heiko,Mecking, Stefan
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p. 430 - 438
(2007/10/02)
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- Regioselectivity of the Singlet Oxygen Ene Reaction (Schenck Reaction) with Vinylsilanes
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The ene reaction of singlet oxygen and vinylsilanes 1 with various substitution patterns and double-bond geometry has been studied. β-Silyl allylic hydroperoxides 2 were the major products of the photooxygenation, accompanied by smaller amounts of α,β-unsaturated ketones 3.The latter derive from decomposition of the regioisomeric α-hydroperoxy silanes 4 by elimination of silanol.Regioselectivities up to 97:3 were observed for vinylsilanes with a methyl group geminal to the silyl group and with cyclic derivatives.Z-Configurated substrates showed lower regioselectivity and reactivity.Elongation of the carbon chain at the geminal position also increased the amount enone formed.These results are rationalized in terms of stereoelectronic effects imposed by the silyl group on the ring-opening of the perepoxide intermediate.
- Adam, Waldemar,Richter, Markus J.
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p. 3335 - 3340
(2007/10/02)
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- Preparation and Reactivities of (η3-1- and 2-Trimethylsiloxyallyl)Fe(CO2)NO Complexes. Intermediates Functioning as Equivalents of β- and α-Acyl Carbocations and Acyl Carbanions
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(η3-1- and 2-Trimethylsiloxyallyl)Fe(CO)2NO complexes were prepared by the reaction of the corresponding siloxyallylic halides with Bu4N.These complexes reacted with both of carbon nucleophiles and carbon electrophiles preferentially at the less hindered sites of the allylic ligands.In these reactions, (η3-1-trimethylsiloxyallyl)Fe(CO)2NO complexes served as synthetically equivalent synthons for both of β-acyl carbocations and β-acyl carbanions and (η3-2-trimethylsiloxyallyl)Fe(CO)2NO complexes as both of α-acyl carbocations and α-acyl carbanions.The stereochemical courses of the reactions are described.
- Itoh, Keiji,Nakanishi, Saburo,Otsuji, Yoshio
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p. 2965 - 2977
(2007/10/02)
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- DIARYLALKANOIDS HAVING ACTIVITY AS LIPOXYGENASE INHIBITORS
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The present invention is novel diarylalkanoids having activity as lipoxygenase inhibitors, novel pharmaceutical compositions therefor, and novel methods of use in treating asthma, allergies, cardiovascular diseases, migraines, psoriasis and immunoinflammatory diseases for diarylalkanoids. The compounds of this invention are also useful as cytoprotective agents.
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- Diarylalkanoids having activity as lipoxygenase inhibitors
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The present invention is novel diarylalkanoids having activity as lipoxygenase inhibitors, novel pharmaceutical compositions therefor, and novel methods of use in treating asthma, allergies, cardiovascular diseases, migraines, psoriasis and immunoinflammatory diseases for diarylalkanoids. The compounds of this invention are also useful as cytoprotective agents.
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- OXIDATION DE LA METHYL ETHYL CETONE COMPARAISON AVEC L'ACETONE ET LA DIETHYLCETONE
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An experimental investigation in a conventional static apparatus of the oxidation of methylethylketone at ca. 350 deg C and subatmospheric pressure confirms the specific features of the reaction, compared with those of the neighbouring ketones, acetone and diethylketone, especially the very long induction period of the first cool flame.To interpret these experimental results, we propose a free radical mechanism based upon the determination of the primary products of the reaction and the evaluation of the rate constants for the elementary steps by the methods of thermochemical kinetics.Contrary to the oxidation reactions of acetone and diethylketone in wich the dominating chain carrier appears to be OH., in the case of methylethylketone HO2. seems to have a key role.It is well known that HO2. cannot be an efficient propagating radical in oxidation reactions and therefore the overall kinetics of the reaction do not trigger off cool flame formation.
- Roux, E. le,Baronnet, F.,Scacchi, G.
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p. 209 - 222
(2007/10/02)
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- The Addition of 1-Lithio-1-(phenylthio)alkanes to 2-(N-Methylanilino)acrylonitrile: An Easy Access to 3-(Phenylthio)ketones and 2-Enones
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A simple and versatile strategy for the synthesis of the title compounds is described.The key-step consists in the addition of 1-lithio-1-(phenylthio)alkanes to 2-(N-methylanilino)acrylonitrile, the nucleophilic phenylthioalkylation of an enol-cation equivalent.Alkylation of the adducts and hydrolysis give 3-(phenylthio)ketones, which can be isolated, or without further purification can be transformed into 2-enones via the well known oxidation-elimination procedure.These reactions are possible with allylic derivatives too, therefore the homologous vinylic compoundscan be prepared by the same way.Pyrolysis of the 1-lithioaminonitriles formed within the first step gives aminonitriles of cyclopropanones via cyclization.
- Ahlbrecht, Hubertus,Ibe, Marcellinus
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p. 210 - 214
(2007/10/02)
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- Preparation of alpha-alkylacroleins
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α-Alkylacroleins are prepared by reacting an alkanal with formaldehyde and a secondary amine in the presence of a carboxylic, dicarboxylic or polycarboxylic acid in certain molar ratios within a pH range of from 2.5 to 7 and at from 0° to 150° C. The α-alkylacroleins which can be prepared by the process described are valuable starting materials for dyes, drugs and pest control agents.
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- PREPARATION DE CETONES ET D'ALCOOLS INSATURES A PARTIR DE LA METHYLVINYLCETONE. UNE SYNTHESE SIMPLE ET EFFICACE D'ALCOOLS ISOPRENIQUES
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The preparation of olefinic ketones and alcohols by means of a retro Diels-Alder reaction is described.This process has been applied to high yield syntheses of linalool 6e, nerolidol 6f and the sesquiterpene alcohol 10 recently isolated from the alga Laurencia nidifica.
- Bloch, R.
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p. 639 - 644
(2007/10/02)
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- Process for preparation of adjacently disubstituted ketones
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A novel 7-hydroxyprostaglandin E1, or a stereoisomer thereof, or a protected derivative thereof, having the following formula: STR1 wherein R8 represents H, CH3 or C2 H5, R9 represents H or CH3, R10 and R11 are identical or different, and each represents H, tetrahydropyranyl or t-butyldimethylsilyl. Also provided is a process for producing an adjacently disubstituted ketone including the above compounds, i.e. 7-oxoprostaglandin, etc. which comprises reacting an α,β-unsaturated carbonyl compound with a cuprous salt and an organolithium compound in an aprotic inert organic medium in the presence of trialkylphosphine, the amounts of said cuprous salt and said organolithium compound being substantially equimolar, and reacting the product with a protected acetal derivative of an organic carbonyl compound or an aldehyde in the presence of a Lewis acid, if necessary, followed by reacting the product with a proton donor.
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- The Mechanism of Ozone-Alkene Reactions in the Gas Phase. A Mass Spectrometric Study of the Reactions of Eight Linear and Branched-Chain Alkenes
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The stable products of the low-pressure (4 - 8 torr (1 torr = 133.33 Pa)) gas-phase reactions of ozone with ethene, propene, 2-methylpropene, cis-2-butene, trans-2-butene, trans-2-pentene, 2,3-dimethyl-2-butene, and 2-ethyl-1-butene have been identified by using a photoionization mass spectrometer coupled to a stirred-flow reactor.The products observed are characteristic of (i) a primary Criegee split to an oxoalkane (aldehyde or ketone) and a Criegee intermediate, (ii) reactions of the Criegee intermediates such as unimolecular decomposition, secondary ozonide formation, etc., and (iii) secondary alkene chemistry involving OH and other free-radical products formed by the unimolecular decomposition of the Criegee intermediates.The secondary OH - alkene - O2 reactions account for a significant fraction of the alkene (CnH2n) consumed and lead to characteristic products such as Cn dioxoalkanes nH2n + 30)>, Cn acyloins nH2n + 32)>, and Cn alkanediols nH2n + 34)>.Cn oxoalkanes and Cn epoxyalkanes observed at m/e (CnH2n + 16) are probably formed primarily via epoxidation of the alkene by O3.A general mechanism has been proposed to account for the observations.
- Martinez, Richard I.,Herron, John T.,Huie, Robert E.
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p. 3807 - 3820
(2007/10/02)
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- Cyclopropanones. Formation of Vinylcyclopropanols and Their Rearrangement to Cyclobutanones
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Vinylcyclopropanols, formed by the addition of vinylmagnesium bromide to the ethyl hemiketal of cyclopropanone, may be converted to cyclobutanone derivatives on reaction with various electrophiles.The ring enlargement of 1-vinyl-2-methylcyclopropanol takes place by preferential migration of the more highly substituted carbon atom.
- Wasserman, Harry H.,Hearn, Michael J.,Cochoy, Robert E.
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p. 2874 - 2880
(2007/10/02)
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