- Production of methyl levulinate from cellulose: Selectivity and mechanism study
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The alcoholysis of cellulose into methyl levulinate (ML) in methanol media was investigated in the presence of several kinds of acid catalyst. One of the synthesized solid niobium-based phosphate catalysts was found to be highly efficient for the generation of ML, reaching an ML yield as high as 56%, higher than the LA yield (52%) in aqueous solution with the same reaction conditions as those used in our previous study (Green Chem., 2014, 16, 3846-3853). More interestingly, in water, very strong Lewis acid promoted the formation of LA; but in methanol, Br?nsted acid enhanced the formation of ML. In-depth investigation showed that the mechanism and type of intermediates of cellulose alcoholysis in methanol were different from those in water and a high Br?nsted/Lewis acid ratio (known as B/L acid ratio) of solid catalysts is needed to prevent the generation of by-products, namely, methyl lactate and 1,1,2-trimethoxyethane. This new-proposed reaction mechanism affected by the B/L acid ratio was very helpful for the design of efficient catalysts.
- Ding, Daqian,Xi, Jinxu,Wang, Jianjian,Liu, Xiaohui,Lu, Guanzhong,Wang, Yanqin
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Read Online
- Oxygenation vs iodonio substitution during the reactions of alkenylsilanes with iodosylbenzene: Participation of the internal oxy group
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Reaction of 4-acyloxybut-1-enylsilanes with iodosylbenzene in the presence of BF3·OEt2 gave 4-acyloxy-2-oxobutylsilane and 3-acyloxytetrahydrofuran-2-ylsilane via a 1,3-dioxan-2-yl cation intermediate, which is generated by participation of the acyloxy group during the electrophilic addition of iodine(iii) to the substrate. The Royal Society of Chemistry.
- Fujita, Morifumi,Lee, Hee Jin,Sugimura, Takashi,Okuyama, Tadashi
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Read Online
- Oxidation of 2-alkylcycloalkanones with iodine-cerium(IV) salts in alcohols
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The reaction of 2-alkylcycloalkanones with iodine-cerium(IV) salts in alcohols (methanol, ethanol, propan-1-ol or propan-2-ol) gave the respective oxo ester in 28-98% yields.
- He, Liangyou,Kanamori, Miyuki,Horiuchi, C. Akira
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Read Online
- Non-Heme Iron Catalysts with a Rigid Bis-Isoindoline Backbone and Their Use in Selective Aliphatic C?H Oxidation
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Iron complexes derived from a bis-isoindoline-bis-pyridine ligand platform based on the BPBP ligand (BPBP=N,N′-bis(2-picolyl)-2,2′-bis-pyrrolidine) have been synthesized and applied in selective aliphatic C?H oxidation with hydrogen peroxide under mild conditions. The introduction of benzene moieties on the bis-pyrrolidine backbone leads to an increased preference of tertiary over secondary C?H bond oxidation (3°/2° ratio up to 33). On the other hand, substituting the meta-position of the pyridines with bulky silyl groups affords enhanced secondary C?H oxidation selectivity and generally leads to higher product yields and mass balances. (Figure presented.).
- Chen, Jianming,Lutz, Martin,Milan, Michela,Costas, Miquel,Otte, Matthias,Klein Gebbink, Robertus J. M.
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- Efficient conversion of levulinic acid into alkyl levulinates catalyzed by sulfonic mesostructured silicas
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Abstract Sulfonic mesoporous silicas have demonstrated an outstanding catalytic performance in the esterification of levulinic acid with different alcohols to produce alkyl levulinates, a family of chemicals considered to be excellent oxygenated fuel extenders for gasoline, diesel and biodiesel. Catalyst screening indicated that propylsulfonic acid-modified SBA-15 material was the most active one, among tested materials, due to a combination of moderately strong sulfonic acid sites with relative high surface hydrophobicity. Under optimized reaction conditions (T = 117°C, ethanol/levulinic acid molar ratio = 4.86/1 and catalyst/levulinic acid = 7 wt%) almost 100% of levulinic acid conversion was achieved after 2 h of reaction, being negligible the presence of levulinic acid by-products or ethers coming from intermolecular dehydration of alcohols. The catalyst has been reused, without any regeneration treatment, up to three times keeping almost the high initial activity. Interestingly, a close catalytic performance to that achieved using ethanol has been obtained with bulkier alcohols.
- Melero,Morales,Iglesias,Paniagua,Hernández,Penedo
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Read Online
- Novel Method for Generation of an Organotin Enolate by the Cleavage of Diketene with Bis(tributyltin) Oxide, and its Michael Reactions
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Generation of a novel type of organotin enolate has been accomplished by the regioselective ring cleavage of diketene with bis(tributyltin) oxide; the enolate afforded the first example of Michael addition in reactions using organotin(IV) enolates.
- Shibata, Ikuya,Nishio, Masahiro,Baba, Akio,Matsuda, Haruo
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Read Online
- Synthesis method of delta-caprolactone spice
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The invention discloses a synthesis method of delta-caprolactone spice, which comprises the following steps of by taking ethyl acetoacetate and methyl acrylate as initial raw materials, adding an alkaline substance with the mass fraction of 0.1-1%, controlling the temperature to be 30-100 DEG C, reacting for 1-8 hours, reacting to obtain acetyl succinate, stirring, heating and washing an acidic substance and acetyl succinate to obtainacetobutyric acid, adding the acetylbutyric acid and hydrogen into a hydrogenation kettle, and performing hydrogenation under the conditions that the temperatureis 60-120 DEG C and the pressure intensity is 0.4-1.2 MPa to obtain delta-caprolactone. The method is simple in process step, high in yield, free of side reaction and simple to separate from impurities, and delta-caprolactone is an important organic compound and an intermediate; the method has a wide application and development prospect in the field of synthesis of essences, fragrances and medicines, and natural products exist in coconut oil, hot milk fat and the like and are widely applied to edible essences and tobacco essences.
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Paragraph 0013; 0023; 0026; 0028; 0031; 0033; 0036; 0038
(2021/02/06)
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- Synthesis method of 4-acetyl butyrate compound
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The invention discloses a synthetic method of a 4-acetyl butyrate compound, and relates to the technical field of chemical synthesis, and the synthetic method comprises the following steps: taking acetone as a reaction solvent and a reactant to react with an acrylate compound under the catalytic action of tetrahydropyrrole; and after the reaction is finished, carrying out post-treatment on the reaction liquid to prepare the 4-acetyl butyrate compound. The method has the advantages of simple reaction system, environment friendliness, cheap and easily available raw materials, simple post-treatment operation, and no need of column chromatography purification, and is beneficial for industrial production.
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Paragraph 0028; 0034-0039
(2021/04/17)
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- Preparation method of delta-caprolactone
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The invention relates to a preparation method of delta-caprolactone. The method comprises the following steps: dissolving a beta-dicarbonyl compound and a basic catalyst in a solvent, and conducting preheating; dropwise adding alkyl acrylate into a reaction system for a Michael addition reaction; cooling the system, adding alkali, and then heating the reaction system for saponification reaction; adding water, cooling the system, and adding a reducing agent for reaction; and cooling the system, adjusting the pH value with acid, and carrying out post-treatment to obtain the delta-caprolactone. The method disclosed by the invention is simple in process operation, high in safety, high in raw material utilization rate, short in total consumed time and free of generation of carbon dioxide.
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Paragraph 0064; 0083-0084; 0086-0087; 0089-0092
(2021/08/25)
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- 3 -substituted indole derivative as well as preparation method and application thereof in antitumor drugs
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The invention relates to 3 -substituted indole derivatives and a preparation method thereof and application thereof in antitumor drugs, wherein the structural formula of 3 -substituted indole derivatives is shown in formula 1 or formula 2. After the synthesized target compound is synthesized, the nuclear magnetic resonance hydrogen spectrum is obtained. The structure of the nuclear magnetic resonance carbon spectrum, the infrared spectrum (only the solid compound), and the mass spectrum (only the target compound) was determined, and its solid intermediate and the target compound melting point were determined by a melting point instrument. 5 - Fluorouracil is used as a positive reference, and through ADMET preliminary prediction of the drug properties and pharmacokinetic properties of the synthesized compound, a CCK - 8 experiment proves that the compound has a good inhibition effect on 3 tumor cells (A549, MCF - 7, NCI - N87). , The novel indole derivative is expected to be a medicine with a higher inhibiting effect on tumors.
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Paragraph 0101-0102
(2021/09/26)
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- Catalytic conversion of ketones to esters: Via C(O)-C bond cleavage under transition-metal free conditions
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The catalytic conversion of ketones to esters via C(O)-C bond cleavage under transition-metal free conditions is reported. This catalytic process proceeds under solvent-free conditions and offers an easy operational procedure, broad substrate scope with excellent selectivity, and reaction scalability. This journal is
- Subaramanian, Murugan,Ramar, Palmurukan M.,Rana, Jagannath,Gupta, Virendra Kumar,Balaraman, Ekambaram
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supporting information
p. 8143 - 8146
(2020/09/09)
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- An efficient method for retro-Claisen-type C-C bond cleavage of diketones with tropylium catalyst
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The retro-Claisen reaction is frequently used in organic synthesis to access ester derivatives from 1,3-dicarbonyl precursors. The C-C bond cleavage in this reaction is usually promoted by a number of transition-metal Lewis acid catalysts or organic Br?nsted acids/bases. Herein we report a new convenient and efficient method utilizing the tropylium ion as a mild and environmentally friendly organocatalyst to mediate retro-Claisen-type reactions. Using this method, a range of synthetically valuable substances can be accessed via solvolysis of 1,3-dicarbonyl compounds.
- Hussein,Huynh,Hommelsheim,Koenigs,Nguyen
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supporting information
p. 12970 - 12973
(2018/11/23)
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- One and Two-Carbon Homologation of Primary and Secondary Alcohols to Corresponding Carboxylic Esters Using β-Carbonyl BT Sulfones as a Common Intermediate
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Herein we report the efficient one- and two-carbon homologation of 1° and 2° alcohols to their corresponding homologated esters via the Mitsunobu reaction using β-carbonyl benzothiazole (BT) sulfone intermediates. The one-carbon homologation approach uses standard Mitsunobu C-S bond formation, oxidation and subsequent alkylation, while the two-carbon homologation uses a less common C-C bond forming Mitsunobu reaction. In this latter case, the use of β-BT sulfone bearing esters lowers the pKa sufficiently enough for the substrate to be used as a carbon-based nucleophile and deliver the homologated β-BT sulfone ester, and this superfluous sulfone group can then be cleaved. In this paper we describe several methods for the effective desulfonylation of BT sulfones and have developed methodology for one-pot alkylation-desulfonylation sequences. As such, overall, a one-carbon homologation sequence can be achieved in a two-pot (four step) procedure and the two-carbon homologation in a two-pot (three step) procedure (three-pot; four step when C-acid synthesis is included). This methodology has been applied to a wide variety of functionality (esters, silyl ethers, benzyls, heteroaryls, ketones, olefins and alkynes) and are all tolerated well providing good to very good overall yields. The power of our method was demonstrated in site-selective ingenol C20 allylic alcohol two-carbon homologation.
- Bon, David J.-Y. D.,Ková?, Ond?ej,Ferugová, Vendula,Zále?ák, Franti?ek,Pospí?il, Ji?í
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p. 4990 - 5001
(2018/05/17)
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- Ligand Effects in the Gold Catalyzed Hydration of Alkynes
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In the gold(I) (e. g. L-Au-OTf) catalyzed hydration of alkynes, the steric hindrance of ligands has a significant influence on the kinetics of the reaction, whereas their electronic effects are less influential. Very low loadings (ppm levels) of a gold catalyst containing a highly sterically hindered phosphine ligand (e. g. L4-Au-OTf) (L4=Me3(OMe)tBuXPhos) is able to catalyze the hydration of a wide range of alkyne substrates in good yields, at relatively low temperature.
- Ebule, Rene E.,Malhotra, Deepika,Hammond, Gerald B.,Xu, Bo
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supporting information
p. 1478 - 1481
(2016/05/19)
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- METHODS OF MAKING ALKYL LACTATES AND ALKYL LEVULINATES FROM SACCHARIDES
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Unique methods have been developed to convert saccharides into value-added products such as alkyl lactates, lactic acid, alkyl levulinates, levulinic acid, and optionally alkyl formate esters and/or hydroxymethylfurfural (HMF). Useful catalysts include Lewis acid catalysts and Br?nsted acid catalysts including mineral acids, metal halides, immobilized heterogeneous catalysts functionalized with a Br?nsted acid group or a Lewis acid group, or combinations thereof. The saccharides are contacted with the catalyst in the presence of various alcohols.
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Page/Page column 4
(2015/02/25)
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- Regioselective oxidation of nonactivated alkyl C-H groups using highly structured non-heme iron catalysts
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Selective oxidation of alkyl C-H groups constitutes one of the highest challenges in organic synthesis. In this work, we show that mononuclear iron coordination complexes Λ-[Fe(CF3SO3) 2((S,S,R)-MCPP)] (Λ-1P), Δ-[Fe(CF3SO 3)2((R,R,R)-MCPP)] (Δ-1P), Λ-[Fe(CF 3SO3)2((S,S,R)-BPBPP)] (Λ-2P), and Δ-[Fe(CF3SO3)2((R,R,R)-BPBPP)] (Δ-2P) catalyze the fast, efficient, and selective oxidation of nonactivated alkyl C-H groups employing H2O2 as terminal oxidant. These complexes are based on tetradentate N-based ligands and contain iron centers embedded in highly structured coordination sites defined by two bulky 4,5-pinenopyridine donor ligands, a chiral diamine ligand backbone, and chirality at the metal (Λ or Δ). X-ray diffraction analysis shows that in Λ-1P and Λ-2P the pinene rings create cavity-like structures that isolate the iron site. The efficiency and regioselectivity in catalytic C-H oxidation reactions of these structurally rich complexes has been compared with those of Λ-[Fe(CF3SO3) 2((S,S)-MCP)] (Λ-1), Λ-[Fe(CF3SO 3)2((S,S)-BPBP)] (Λ-2), Δ-[Fe(CF 3SO3)2((R,R)-BPBP)] (Δ-2), Λ-[Fe(CH3CN)2((S,S)-BPBP)](SbF6) 2 (Λ-2SbF6), and Δ-[Fe(CH3CN) 2((R,R)-BPBP)](SbF6)2 (Δ-2SbF 6), which lack the steric bulk introduced by the pinene rings. Cavity-containing complexes Λ-1P and Λ-2P exhibit enhanced activity in comparison with Δ-1P, Δ-2P, Λ-1, Λ-2, and Λ-2SbF6. The regioselectivity exhibited by catalysts Λ-1P, Λ-2P, Δ-1P, and Δ-2P in the C-H oxidation of simple organic molecules can be predicted on the basis of the innate properties of the distinct C-H groups of the substrate. However, in specific complex organic molecules where oxidation of multiple C-H sites is competitive, the highly elaborate structure of the catalysts allows modulation of C-H regioselectivity between the oxidation of tertiary and secondary C-H groups and also among multiple methylene sites, providing oxidation products in synthetically valuable yields. These selectivities complement those accomplished with structurally simpler oxidants, including non-heme iron catalysts Λ-2 and Λ-2SbF6.
- Gómez, Laura,Canta, Merceì,Font, David,Prat, Irene,Ribas, Xavi,Costas, Miquel
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p. 1421 - 1433
(2013/03/29)
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- An iron catalyst for oxidation of alkyl C-H bonds showing enhanced selectivity for methylenic sites
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Many are called but few are chosen: A nonheme iron complex catalyzes the oxidation of alkyl C-H bonds by using H2O2 as the oxidant, showing an enhanced selectivity for secondary over tertiary C-H bonds (see scheme). Copyright
- Prat, Irene,Gomez, Laura,Canta, Merce,Ribas, Xavi,Costas, Miquel
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supporting information
p. 1908 - 1913
(2013/03/14)
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- Cp* iridium precatalysts for selective C-h oxidation with sodium periodate as the terminal oxidant
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Sodium periodate (NaIO4) is shown to be a milder and more efficient terminal oxidant for C-H oxidation with CpIr (Cp* = C 5Me5) precatalysts than ceric(IV) ammonium nitrate. Synthetically useful yields, regioselectivities, and functional group tolerance were found for methylene oxidation of substrates bearing a phenyl, ketone, ester, or sulfonate group. Oxidation of the natural products (-)-ambroxide and sclareolide proceeded selectively, and retention of configuration was seen in cis-decalin hydroxylation. At 60 C, even primary C-H bonds can be activated: whereas methane was overoxidized to CO2 in 39% yield without giving partially oxidized products, ethane was transformed into acetic acid in 25% yield based on total NaIO4. 18O labeling was demonstrated in cis-decalin hydroxylation with 18OH2 and NaIO 4. A kinetic isotope effect of 3.0 ± 0.1 was found in cyclohexane oxidation at 23 C, suggesting C-H bond cleavage as the rate-limiting step. Competition experiments between C-H and water oxidation show that C-H oxidation of sodium 4-ethylbenzene sulfonate is favored by 4 orders of magnitude. In operando time-resolved dynamic light scattering and kinetic analysis exclude the involvement of metal oxide nanoparticles and support our previously suggested homogeneous pathway.
- Zhou, Meng,Hintermair, Ulrich,Hashiguchi, Brian G.,Parent, Alexander R.,Hashmi, Sara M.,Elimelech, Menachem,Periana, Roy A.,Brudvig, Gary W.,Crabtree, Robert H.
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supporting information
p. 957 - 965
(2013/04/23)
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- Combined effects on selectivity in Fe-catalyzed methylene oxidation
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Methylene C-H bonds are among the most difficult chemical bonds to selectively functionalize because of their abundance in organic structures and inertness to most chemical reagents. Their selective oxidations in biosynthetic pathways underscore the power of such reactions for streamlining the synthesis of molecules with complex oxygenation patterns. We report that an iron catalyst can achieve methylene C-H bond oxidations in diverse natural-product settings with predictable and high chemo-, site-, and even diastereoselectivities. Electronic, steric, and stereoelectronic factors, which individually promote selectivity with this catalyst, are demonstrated to be powerful control elements when operating in combination in complex molecules. This small-molecule catalyst displays site selectivities complementary to those attained through enzymatic catalysis.
- Chen, Mark S.,White, M. Christina
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scheme or table
p. 533 - 571
(2010/10/05)
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- Direct benzylation and allylic alkylation in high-temperature water without added catalysts
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In high-temperature water a series of benzyl and allylic alcohols reacted with 1,3-dicarbonyl compounds and activated aromatic compounds to give the alkylated products without added catalysts.
- Hirashita, Tsunehisa,Kuwahara, Sho,Okochi, Sota,Tsuji, Makoto,Araki, Shuki
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scheme or table
p. 1847 - 1851
(2010/09/07)
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- Studies towards the synthesis of 13C-labelled anthocyanins
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The anthocyanins are a class of polyphenols found in nature, which are widely distributed throughout the plant kingdom and are thought to possess antioxidant properties. Methodology previously developed in our group for the regioselective placement of 13C-atoms into aromatic rings is being applied to the synthesis of 13C-labelled anthocyanins-namely cyanidin-3-glucoside and delphinidin-3-glucoside. Copyright
- Marshall, Laura J.,Cable, Karl M.,Botting, Nigel P.
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scheme or table
p. 315 - 318
(2011/05/02)
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- Process For Preparing Porphyrin Derivatives, Such As Protoporphyrin (IX) And Synthesis Intermediates
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The present invention relates to a process for preparing a porphyrin of formula (I), optionally in the form of a salt with an alkali metal and/or in the form of a metal complex: in which: R and R′ are as defined in claim 1, comprising: a step of condensation, in an acidic medium, between a dipyrromethane of formula (II): in which R′b is as defined above for (I), and a dipyrromethane of formula (III): in which R″ is as defined in claim 1, and also the compounds of formula (III).
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Page/Page column 14-15
(2008/12/07)
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- PYRIMIDINE DERIVATIVE
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This invention provides pyrimidine derivatives represented by a formula, in the formula, ring A stands for carbocyclic group or heterocyclic group, X 1 stands for hydrogen, lower alkyl, amino, etc., X 2 stands for hydrogen or lower alkyl, Y stands for a direct bond or sulfur or nitrogen, n stands for an integer of 0 - 4, and Ar stands for a group of the following formula, or a salt thereof, which concurrently exhibit 5-HT 1A agonistic activity and 5-HT 3 antagonistic activity and are useful for therapy and treatments of diseases such as IBS. The invention furthermore provides a therapeutic method of IBS, characterized by having 5-HT 1A agonistic activity and 5-HT 3 antagonistic activity work simultaneously and cooperatively in vivo, which comprises either administering 5-HT 3 antagonistic agent which concurrently exhibits 5-HT 1A agonistic activity, or administering 5-HT 1A agonistic agent and 5-HT 3 antagonistic agent simultaneously, in sequence or at an interval.
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Page/Page column 75
(2010/11/24)
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- Synthesis of biologically active substances based on phenoxyethanol derivatives
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By reaction of phenoxyethanol with diverse structure acyl chlorides phenoxyethanol esters were synthesized containing in the molecule fragments of undecene acid and also of some ketocarboxylic acids. The latter acids were obtained by ozonation of alkylcyclenes. 2005 Pleiades Publishing, Inc.
- Kukovinets,Yamansarova,Kasradze,Lozhkina,Zainullin,Abdullin
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p. 673 - 677
(2007/10/03)
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- Ruthenium catalysed oxidation without CCl4 of oleic acid, other monoenic fatty acids and alkenes
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Ruthenium catalysed oxidation of alkenes and monoenic fatty acids is reported. The study of the influence of cosolvents (H2O/MeCN/X) shows that toxic CCl4 initially used in the Sharpless system (H 2O/MeCN/CCl4) can be avoided and demonstrates that the oxidative cleavage of CC bond could be accomplished in good yields with H 2O/MeCN/AcOEt solvent system in a ratio 3/2/2, respectively.
- Zimmermann, Fran?ois,Meux, Eric,Mieloszynski, Jean-Luc,Lecuire, Jean-Marie,Oget, Nicolas
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p. 3201 - 3203
(2007/10/03)
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- DIFLUOROALKENE DERIVATIVE, PEST CONTROL AGENT CONTAINING THE SAME, AND INTERMEDIATE THEREFOR
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A difluoroalkene derivative which is sufficiently effective in controlling various pests even when used in a small dose and is highly safe for crops, natural enemies to the pests, and animals; and an intermediate for the derivative. The difluoroalkene derivative is represented by the general formula: [I] wherein L1 and L2 are the same or different and each represents oxygen or sulfur; n is an integer of 2 to 8; and Q represents a 5- to 12-membered heterocyclic group having any desired heteroatom selected among nitrogen, oxygen, and sulfur.
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- Synthesis and spectroscopic characterization of [5-13C]- and [6-13C]ubiquinone-10 for studies of bacterial photosynthetic reaction centers
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This paper presents the synthesis and characterization by mass spectrometry and NMR spectroscopy of [2-13C]- and [3-13C]ubiquinone-0 and of [5-13C]- and [6-13C]ubiquinone-10. A scheme based on the synthetic approach to [5-13C]ubiquinone-10 has been worked out for the synthesis of ubiquinones 13C-labeled at any individual position and at every combination of positions in the quinone ring. The [5-13C]- and [6-13C]ubiquinone-10 isotopomers were incorporated into the QA-site of the photosynthetic reaction center of Rhodobacter sphaeroides R-26. Magic angle spinning NMR subsequently revealed an unperturbed 6-position, while the signal of the 5-position was absent. These results corroborate the recently reported detection of an asymmetric binding of QA with a dynamic perturbation involving the 4-carbonyl functionality.
- Boers, Rutger B.,Gast, Peter,Hoff, Arnold J.,De Groot, Huub J. M.,Lugtenburg, Johan
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p. 189 - 202
(2007/10/03)
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- One-pot and sequential asymmetric hydrogenation of β,δ-diketoesters into functionalized 1,3-diols: From anti- to syn-stereoselectivity
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The asymmetric hydrogenation of methyl 3,5-dioxohexanoate (1) into mixtures of 3,5-dihydroxyesters (2) and 3-hydroxylactones (3) has been reinvestigated with a variety of ruthenium catalysts. Catalysts bearing diphosphanes which possess axial chirality such as (S)-MeO-Biphep give predominantly (3R,5S)-anti-2 in up to 78% de and 95% ee, affording an efficient synthesis of (S)-6-methyl-5,6-dihydro-2-pyrone [(S)-5] in up to 95% enantiomeric excess. On the contrary, some Ru-{amidophosphane-phosphinite} complexes catalyze sluggishly the formation of syn-2 in up to 92% de but with poor enantiomeric excesses. In all cases, methyl (R)-3-hydroxy-5-oxohexanoate [(R)-11] is the exclusive primary hydrogenation product, which can be isolated in high yields and enantiomeric excesses up to 78%. Further hydrogenation of enantiomerically enriched (R)-11 in a separate experiment affords (3R,5R)-syn-2 in high diastereomeric and enantiomeric excesses (up to 80% and 98%, respectively), provided a Ru-(R)-Binap-type catalyst is used.
- Blandin, Veronique,Carpentier, Jean-Francois,Mortreux, Andre
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p. 3421 - 3427
(2007/10/03)
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- Oxidation of 2-substituted cycloalkanones with cerium(IV) sulfate tetrahydrate in alcohols and acetic acid
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The reaction of 2-substituted cycloalkanones with cerium(IV) sulfate tetrahydrate (CS) in alcohols and acetic acid gave the corresponding alkyl esters of oxo acids (80-96%) and oxo acids (78-96%), respectively, by oxidative cleavage of the C(R).C=O bond. In the case of 2-iodocycloalkanones in methanol, the dimethyl ester was obtained in good yield. A treatment of 5α-cholestan-3-one with CS in methanol produced 2-acetal 3-ester of 2,3-seco derivative in good yield. The effects of cerium(IV) and copper(II) salts are also discussed.
- He, Liangyou,Horiuchi, C. Akira
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p. 2515 - 2521
(2007/10/03)
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- Gas-Phase Reactions of 1,2-Dimethylcyclopentene and of 2,6-Heptanedione with Ozone: Unprecedented Formation of an Ozonide by Ozone Treatment of a Diketone
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Gas-phase ozonizations of 1,2-dimethylcyclopentene (1) and of 2,6-heptanedione (5) afforded in each case dimethylcyclopentene ozonide (2) in low yields. In the ozonization of 1, diketone 5 was formed as the single major product, along with nine "abnormal" ozonolysis products which were formed by oxidative cleavage of carbon-carbon single bonds.
- Griesbaum, Karl,Miclaus, Vasile,Jung, Chan,Quinkert, Ralf-Olaf
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p. 627 - 629
(2007/10/03)
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- Acid-catalyzed reactions of six- and seven-membered cyclic hemiperacetals and peracetals and of related bicyclic ozonides
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HCl-catalyzed reactions of the hemiperacetals 3-methoxy-3-methyl-7-hydroxy-1,2-dioxepane (1a) and 3-methoxy-3-methyl-6-hydroxy-1,2-dioxane (1b) and of the related ozonides 1-methyl-6,7,8-trioxabicyclooctane (2a) and 1-methyl-5,6,7-trioxabicycloheptane (2b) gave peroxidic monocyclic (11-13), bicyclic (14), and (or) tricyclic (15) products.By contrast, reactions of the peracetals corresponding to 1a and 1b, viz., 3-methyl-3,7-dimethoxy-1,2-dioxepane (13a) and 3-methyl-3,6-dimethoxy-1,2-dioxane (13b) gave only non-peroxide products.Reactions of the persubstituted peracetals 3,6-dimethoxy-3,6-dimethyl-1,2-dioxane (25) and 3,6-dimethoxy-3-isopropyl-6-methyl-1,2-dioxane (27) also gave non-peroxidic products, which resulted from fragmentation of the carbon skeletons.
- Griesbaum, Karl,Kiesel, Gilbert,Mertens, Henri,Krieger-Beck, Petra,Henke, Henning
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p. 2198 - 2204
(2007/10/02)
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- Ozonolyses of Olefins with Chloro Substituents in Vinylic Positions on Polyethylene
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Ozonolyses of the chloro-substituted 5- and 6-membered cycloolefins 20a, 20b and 30a-c on polyethylene afforded the corresponding chloro-substituted ozonides.The thermal decomposition of these ozonides is described.Ozonolyses of the same olefins in solution and of the acyclic chloro olefins 5 and 8 both on polyethylene and in solution gave no ozonides.
- Griesbaum, Karl,Greinert, Reinhard
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p. 391 - 397
(2007/10/02)
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- Leukotriene LTD4 and LTB4 antagonists
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This invention encompasses compounds of Formula I STR1 and the pharmaceutically acceptable salts and geometrical and optical isomers thereof wherein: X, Y, and Z are each independently O or S with S optionally oxidized to S=O; Alk is straight or branched chain alkylene or hydroxyalkylene containing 1-6 carbon atoms; R1 is hydrogen or lower alkyl; n is 0 to 5; R2 is hydrogen, lower alkyl, cycloalkyl, --(CH2)n --CO2 R1, phenyl, phenyl substituted with halo, lower alkyl or lower alkoxy; and Ar is 5,6,7,8-tetrahydro-1-naphthalenyl, phenyl, or phenyl substituted with lower alkyl, hydroxy, lower alkoxy, or lower alkanoyl. This invention is in the field of pharmaceutical agents which act as leukotriene D4 (LTD4) antagonists and includes embodiments which act as leukotriene B4 (LTD4) antagonists.
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- Stereoselective Synthesis and Stereochemical Determination of 2,5-Dialkylpyrrolidines and 2,6-Dialkylpiperidines
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ω-Alkyllactams 3 can be transformed into ω-alkyl cyclic β-enaminoesters 7 which are good precursors of insects venom alkaloids.A stereoselective synthesis of dialkylpyrrolidines and Solenopsine A is described followed by and easy stereochemical determination by 13C nmr.
- Bacos, D.,Celerier, J. P.,Marx, E.,Rosset, S.,Lhommet, G.
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p. 1387 - 1392
(2007/10/02)
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- Leukotriene LTD4 and LTB4 antagonists
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The invention encompasses compounds of Formula I STR1 and the pharmaceutically acceptable salts and geometrical and optical isomers thereof wherein: X, Y, and Z are each independently O or S with S optionally oxidized to S=O; Alk is alkylene or hydroxyalkylene containing 1-6 carbon atoms; R1 is hydrogen or lower alkyl; n is 0 to 5; R2 is hydrogen, lower alkyl, cycloalkyl, --(CH2)n --CO2 R1, phenyl, phenyl substituted with halo, lower alkyl or lower alkoxy; and Ar is 5,6,7,8-tetrahydro-1-naphthalenyl, phenyl, or phenyl substituted with lower alkyl, hydroxy, lower alkoxy, or lower alkanoyl. The compounds are useful as anti-allergy agents and anti-inflammatory agents.
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- CUPRIC ION-CATALYZED DIOXYGENATION OF 1,2-CYCLOHEXANEDIONES. A NONENZYMATIC ANALOG FOR QUERCETINASE DIOXYGENATION
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1,2-Cyclohexanediones were found to be dioxygenated by molecular oxygen with the aid of cupric ion to afford 1,5-keto acids and carbon monoxide.The reaction proceeds possibly via an endoperoxide intermediate.Methyl α-hydroxyadipates were also formed as byproducts.The mechanism of oxygenation is discussed.
- Utaka, Masanori,Hojo, Makoto,Fujii, Yasuyuki,Takeda, Akira
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p. 635 - 638
(2007/10/02)
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- Synthesis of the Lycopodium Alkaloid rac-α-Obscurine by 1,3-Annulation of an Enimine
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Acid catalysed 1,3-annulation of 1,2,3,4-tetrahydro-6-methyl-2-oxopyridine (1) to the enimine 3, followed by methylation, provides a new regio and stereoselective route to rac-α-obscurine (5).Reduction of rac-N-desmethyl-α-obscurine with LiAlH4 yields rac-lycodine (11) and rac-deacetylflabellidine (9).A new pathway for the biogenesis of the β-amino-imine 9 is suggested.
- Schumann, Dieter,Naumann, Anneliese
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p. 220 - 225
(2007/10/02)
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- Meerwein Saponification of Alkyl 3-Oxoalkanoates in the Gas Chromatograph
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Alkyl 3-oxoalkanoates decompose by unevitable traces of water in the gas chromatograph to yield the corresponding methyl ketones and alcohols (Meerwein saponification).Decomposition occurs in the hot injector (T= 270 deg C) of the gas chromatograph and also on glass capillary columns (T> 160 deg C).Decomposition in routine work can be avoided by preparing the corresponding 3-trimethylsilyl enol ethers.
- Thoma, Heinz,Spiteller, Gerhard
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p. 1237 - 1248
(2007/10/02)
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- Chemistry of Ketene Acetals. 7. 2-Methoxy-4H-pyrans as Strong Hydride Donors in Reactions with Electrophilic Olefins
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The reactions of 2-methoxy-5,6-dihydropyrans (2) and 2-methoxy-4H-pyrans (3) with a variety of electrophilic olefins R4R5C=C(CN)X have been studied.Cyclobutanes are formed in an equilibrium reaction from 2 as well as 3.In general, the compounds 3 give ultimately the thermodynamically stable heptadienoic esters 10. 2-Methoxy-4H-pyrans, substituted at carbon atom 6, yield, however, a pyrone derivative (11) when they react with strongly electrophilic olefins substituted with three or four electron-withdrawing groups.Both conversions are supposed to occur via the abstraction of a hydride ion from C(4) in a rate-determining step leading to a pyrylium ion (14).The further course of the process is determined by the character of the nucleophile formed in the addition of the hydride ion to the olefin and by the substitution pattern of 3.
- Bakker, C. G.,Hazen, C. J. J. M.,Scheeren, J. W.,Nivard, R. J. F.
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p. 2736 - 2742
(2007/10/02)
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- ETUDE DES PETITS CYCLES-XLIV. UNE VOIE DE SYNTHESE DES ACYL-2 CYCLOBUTANONES
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Organic peracid oxidation of α-cyclopropylidene ketones and acetals substituted in the vinylic position leads to the corresponding oxaspiropentyl ketones and acetals.Esters are also formed from the products of the Baeyer-Villiger oxidation; they are easily removed from the crude product.Unsubstituted oxaspiropentyl ketones are not obtained by this method; they are obtained by oxidation of oxaspiropentyl alcohols ( formed by epoxidation of α-cyclopropylidene alcohols).The isomerisation, either spontaneous or through reaction with lithium halides, of oxaspiropentyl ketones and acetals, gives 2-acyl-cyclobutanones and corresponding mono-acetals.These new unstable 1,3-diones must be stored in CCl4 solution.They are present in the dione form only.They add water and methanol, in acidic and even in neutral medium, leading to ring opening products. 2-Benzoyl cyclobutanone 4g is easily rearranged into 3,4-dihydro-6-phenyl 2-pyrone 12.Deacetalization of the 2-acyl-cyclobutanones mono-acetals 7B-11b into the corresponding diones is not possible even by the moist silicagel technique.
- Lechevallier, A.,Huet, F.,Conia, J.M.
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p. 3329 - 3336
(2007/10/02)
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- Decarbonylation of Tetrahydrofuran-2-carboxylic Acids and Tetrahydropyrane-2-carboxylic Acids in Concentrated Sulfuric acid: Formation of Oxonium Ions
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Tetrahydrofuran-2-carboxylic acids 1, 3, and 5 readily decarbonylate in 96percent sulfuric acid, generating stable oxonium ions 2, 4, and 6, respectively.Analogously, tetrahydropyran-2-carboxylic acids 7, 9, 12, and 14a produce oxonium ions 8, 10, 13, and 15, respectively.These oxonium ions are quite stable, with the exception of 10, which partially isomerizes to 11, and 13, which rearranges to ions 17 and 21.Details in the transformation of oxonium ion 15 into lactone 23 by way of open chain acid 22a were elucidated.
- Bates, Hans Aaron
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p. 2490 - 2493
(2007/10/02)
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- Process for the preparation of delta keto-acids and derivatives thereof
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A process is described for the preparation of delta keto-acids wherein there is used as a catalyst the condensation adduct of a cyclic secondary amine with an α-β-acrylic-type unsaturated compound, providing high selectivity and conversion results.
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- Preparation of delta-keto-esters
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Delta-keto-esters such as 4-oxopentane-1-carboxylic acid methyl ester and the like, are prepared in the presence of a primary amine, a Schiff base, or both, by reacting a ketone having at least one hydrogen atom in the alpha position and an alpha-beta unsaturated carboxylic acid ester in the presence of an acid according to the disclosed invention.
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- LIGHT-INDUCED FREE-RADICAL REACTIONS OF 2-METHOXY-6-METHYLTETRAHYDROPYRAN: IRREVERSIBLE RING OPENING AND MULTISITE HYDROGEN ABSTRACTION
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Acetophenone-initiated photodegradation of cis-2-methoxy-4-methyltetrahydropyran (7) in benzene solvent produced six products.The structures of the products, and studies using optically active 7, showed that hydrogen abstraction occurs at both C-2 and C-6 of the tetrahydropyran ring.The products derived from the C-2 radical indicated two pathways for this radical: ring opening and loss of methyl, which is consistent with previous work on other similar systems.Results with optically active 7 showed that the ring-opening pathway is irreversible.Generation of an open-chain radical independently also showed that cyclization to a six membered ring does not occur.The products from the photodegradation were trans-2-methoxy-6-methyltetrahydropyran (8), methyl hexanoate (10), 6-methyltetrahydropyran-2-one (9), methyl 5-phenylhexanoate (11), 1,7-dimethyl-7-phenyl-6,8-dioxobicyclooctane (13), and 2-methoxy-2-(1-phenyl-1-hydroxyethyl)-6-methyltetrahydropyran (12).The yield of lactone 9 was found to be sensitive to the amount of residual oxygen present during the photolysis.
- Babcock, Bruce W.,Dimmel, Donald R.,Graves, David P.,McKelvey, Ronald D.
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p. 736 - 742
(2007/10/02)
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- 2-ACYLCYCLOBUTANONES FROM α-CYCLOPROPYLIDENE KETONES
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Oxaspiropentyl ketones and acetals prepared from α-cyclopropylidene ketones and acetals undergo, with lithium halides, isomerisation to 2-acylcyclobutanones and monoacetals.
- Huet, Francois,Lechevallier, Andre,Conia, Jean-Marie
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p. 1515 - 1518
(2007/10/02)
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- Prostaglandins in human seminal plasma. Prostaglandins and related factors 46.
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This study on human seminal plasma sought after the compounds which either possess the dienone chromophore or can be converted into it by treatment with sodium hydroxide. In addition, this investigation led to the isolation of 8 more (PGs) prostaglandins which were present in higher concentrations than the previously recognized PGs. Samples of human seminal plasma were subjected to silicic acid chromatography, reversed phase partition chromatography, thin layer chromatography, and gas liquid chromatography which isolated those 8 PGs not previously recognized. 4 of these compounds, PGE1-217, PGE2-217, PGE1-278, and PGE2-278 were known from earlier studies but had not been isolated from natural sources. The other 4 were 19 hydroxy derivatives of the 4 abovementioned compounds. The concentrations of the previously recognized PGs were recently determined and it was found that the 19 hydroxy derivatives were present in concentrations 4 times higher than the PGE compounds.
- Hamberg,Samuelsson
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p. 257 - 263
(2007/10/06)
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