- A simple and regioselective carbon-oxygen bond cleavage using Niobium(V)
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A simple and convenient method for the differentiation of alkoxy groups on aromatic rings is described. Niobium(V) is found to possess a strong Lewis acid property to transform alkyl arylethers smoothly to the corresponding phenols in high yields. The excellent regioselectivity was also observed in dialkoxy benzene derivatives under mild conditions.
- Arai, Shigeru,Sudo, Yukinori,Nishida, Atsushi
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Read Online
- Biomimetic Design of a 3 D Transition Metal/Carbon Dyad for the One-Step Hydrodeoxygenation of Vanillin
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Enzyme catalysts always show an excellent catalytic selectivity, which is important in biochemistry, especially in catalytic synthesis and biopharming. This selectivity is achieved by combining the binding effect induced by the electrostatic effect of the enzyme to attract a specific substrate and then the prearrangement of the substrates inside the enzyme pocket. Herein, we report a proof-of-concept application of an interfacial electrostatic field induced by constructing Schottky heterojunctions to mimic the electrostatic catalysis of an enzyme. In combination with the 3 D structure, a transition metal/carbon dyad was designed by nanoconfinement methods to promote the differential binding effect and the space-induced organization of the reaction intermediate (vanillyl alcohol) to develop a new one-step hydrogenolysis of vanillin for the production of 2-methoxy-4-methylphenol with a remarkably high selectivity (>99 %).
- Chen, Jie-Sheng,Li, Xin-Hao,Su, Juan,Wang, Hong-Hui,Zhang, Jun-Jun,Zhao, Tian-Jian
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Read Online
- Encapsulated Ni-Co alloy nanoparticles as efficient catalyst for hydrodeoxygenation of biomass derivatives in water
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Catalytic hydrodeoxygenation (HDO) is one of the most promising strategies to transform oxygen-rich biomass derivatives into high value-added chemicals and fuels, but highly challenging due to the lack of highly efficient nonprecious metal catalysts. Herein, we report for the first time of a facile synthetic approach to controllably fabricate well-defined Ni-Co alloy NPs confined on the tip of N-CNTs as HDO catalyst. The resultant Ni-Co alloy catalyst possesses outstanding HDO performance towards biomass-derived vanillin into 2-methoxy-4-methylphenol in water with 100% conversion efficiency and selectivity under mild reaction conditions, surpassing the reported high performance nonprecious HDO catalysts. Impressively, our experimental results also unveil that the Ni-Co alloy catalyst can be generically applied to catalyze HDO of vanillin derivatives and other aromatic aldehydes in water with 100% conversion efficiency and over 90% selectivity. Importantly, our DFT calculations and experimental results confirm that the achieved outstanding HDO catalytic performance is due to the greatly promoted selective adsorption and activation of C=O, and desorption of the activated hydrogen species by the synergism of the alloyed Ni-Co NPs. The findings of this work affords a new strategy to design and develop efficient transition metal-based catalysts for HDO reactions in water.
- Chen, Chun,Gong, Wanbing,Han, Miaomiao,Wang, Dongdong,Wang, Guozhong,Zhang, Haimin,Zhang, Jifang,Zhang, Yunxia,Zhao, Huijun
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p. 2027 - 2037
(2021/09/02)
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- Thiols Act as Methyl Traps in the Biocatalytic Demethylation of Guaiacol Derivatives
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Demethylating methyl phenyl ethers is challenging, especially when the products are catechol derivatives prone to follow-up reactions. For biocatalytic demethylation, monooxygenases have previously been described requiring molecular oxygen which may cause oxidative side reactions. Here we show that such compounds can be demethylated anaerobically by using cobalamin-dependent methyltransferases exploiting thiols like ethyl 3-mercaptopropionate as a methyl trap. Using just two equivalents of this reagent, a broad spectrum of substituted guaiacol derivatives were demethylated, with conversions mostly above 90 %. This strategy was used to prepare the highly valuable antioxidant hydroxytyrosol on a one-gram scale in 97 % isolated yield.
- Grimm, Christopher,Kroutil, Wolfgang,Pompei, Simona,Schiller, Christine,Schober, Lukas
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supporting information
p. 16906 - 16910
(2021/07/02)
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- Oxygen-Free Regioselective Biocatalytic Demethylation of Methyl-phenyl Ethers via Methyltransfer Employing Veratrol- O-demethylase
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The cleavage of aryl methyl ethers is a common reaction in chemistry requiring rather harsh conditions; consequently, it is prone to undesired reactions and lacks regioselectivity. Nevertheless, O-demethylation of aryl methyl ethers is a tool to valorize natural and pharmaceutical compounds by deprotecting reactive hydroxyl moieties. Various oxidative enzymes are known to catalyze this reaction at the expense of molecular oxygen, which may lead in the case of phenols/catechols to undesired side reactions (e.g., oxidation, polymerization). Here an oxygen-independent demethylation via methyl transfer is presented employing a cobalamin-dependent veratrol-O-demethylase (vdmB). The biocatalytic demethylation transforms a variety of aryl methyl ethers with two functional methoxy moieties either in 1,2-position or in 1,3-position. Biocatalytic reactions enabled, for instance, the regioselective monodemethylation of substituted 3,4-dimethoxy phenol as well as the monodemethylation of 1,3,5-trimethoxybenzene. The methyltransferase vdmB was also successfully applied for the regioselective demethylation of natural compounds such as papaverine and rac-yatein. The approach presented here represents an alternative to chemical and enzymatic demethylation concepts and allows performing regioselective demethylation in the absence of oxygen under mild conditions, representing a valuable extension of the synthetic repertoire to modify pharmaceuticals and diversify natural products.
- Grimm, Christopher,Lazzarotto, Mattia,Pompei, Simona,Schichler, Johanna,Richter, Nina,Farnberger, Judith E.,Fuchs, Michael,Kroutil, Wolfgang
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p. 10375 - 10380
(2020/10/02)
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- Regioselectivity of Cobalamin-Dependent Methyltransferase Can Be Tuned by Reaction Conditions and Substrate
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Regioselective reactions represent a significant challenge for organic chemistry. Here the regioselective methylation of a single hydroxy group of 4-substituted catechols was investigated employing the cobalamin-dependent methyltransferase from Desulfitobacterium hafniense. Catechols substituted in position four were methylated either in meta- or para-position to the substituent depending whether the substituent was polar or apolar. While the biocatalytic cobalamin dependent methylation was meta-selective with 4-substituted catechols bearing hydrophilic groups, it was para-selective for hydrophobic substituents. Furthermore, the presence of water miscible co-solvents had a clear improving influence, whereby THF turned out to enable the formation of a single regioisomer in selected cases. Finally, it was found that also the pH led to an enhancement of regioselectivity for the cases investigated.
- Pompei, Simona,Grimm, Christopher,Farnberger, Judith E.,Schober, Lukas,Kroutil, Wolfgang
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p. 5977 - 5983
(2020/10/06)
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- Nickel-catalyzed intelligent reductive transformation of the aldehyde group using hydrogen
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The selective transformation of the aldehyde group (-CHO) in multifunctional oxygenates is a key challenge in the development of sustainable biomass feedstock. Herein, a smart Ni-MFC catalyst was developed from a 2D Ni-based metal-organic framework (MOF), which efficiently promoted the transformation of -CHO in the presence of H2 to a methyl group (-CH3) via the reductive etherification and hydrogenolysis of the C-O ether bond in methanol. Moreover, the catalytic process could be controlled to directionally produce methyl ether (-CH2OR) using the reductive etherification protocol. For the catalytic reduction of vanillin, the Ni-MFC-700 catalyst guaranteed the full conversion of vanillin and 96.5% yield of the desired 2-methoxy-4-methylphenol (MMP), while the Ni-MFC-500 catalyst afforded about 82.7% yield of 4-(methoxymethyl)-2-methoxyphenol in methanol solvent. This is a novel and promising approach for the valorization of multifunctional oxygenates and biomass-derived platform compounds.
- Tong, Xinli,Guo, Pengfei,Liao, Shengyun,Xue, Song,Zhang, Haigang
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p. 5828 - 5840
(2019/11/11)
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- Role of copper- or cerium-promoters on NiMo/Γ-Al2O3 catalysts in hydrodeoxygenation of guaiacol and bio-oil
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Effect of copper (Cu) or cerium (Ce) as promoters for nickel-molybdenum/γ-alumina (NiMo/γ-Al2O3) catalyst on the hydrodeoxygenation (HDO) of guaiacol (GUA), a model oxygenated compound found in a bio-oil derived from woody biomass, was comparatively investigated. The addition of Cu- or Ce-promoters affected the physicochemical properties of the NiMo catalyst. The NiMo catalyst promoted by Cu showed the higher reducibility, whilst the Ce-promoter (2–8 wt% based on γ-Al2O3 content) provided the NiMo catalyst with a higher distribution of active metals and induced a greater difficulty in the reduction under hydrogen (H2) atmosphere. For the HDO of GUA at a mild reaction condition (10 bar initial H2 pressure and 300 °C) in the absence of solvent, the Cu-promoter enhanced the hydrogenation activity of the NiMo catalyst to convert GUA to phenol and methylphenols, one-atomic oxygen species. Whereas, the addition of Ce obviously inhibited the formation of coke on the catalyst surface after a long reaction period (6 h) and gave a higher GUA conversion level with increasing yield of phenols. For the HDO of real bio-oil obtained from the fast pyrolysis of cassava rhizome, the NiMo catalysts promoted by Cu or Ce at 4 wt% based on the γ-Al2O3 content showed a higher performance at eliminating the oxygenated compounds in the bio-oil, reducing the oxygen/carbon (O/C) molar ratio by over seven-fold from 1.75 to 0.24–0.25. Moreover, the gross heating value of the bio-oil was improved from 21.5 to ca. 29.0 MJ/kg after the HDO process. However, the addition of the Cu or Ce promoter did not inhibit coke deposition, possibly due to the acidic properties of the bio-oil that deteriorated the catalyst performance by metal leaching.
- Sangnikul, Patiphat,Phanpa, Chanisara,Xiao, Rui,Zhang, Huiyan,Reubroycharoen, Prasert,Kuchonthara, Prapan,Vitidsant, Tharapong,Pattiya, Adisak,Hinchiranan, Napida
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p. 151 - 160
(2019/02/17)
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- Catalytic Hydrogenolysis of Substituted Diaryl Ethers by Using Ruthenium Nanoparticles on an Acidic Supported Ionic Liquid Phase (Ru@SILP-SO3H)
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Catalytic hydrogenolysis of diaryl ethers is achieved by using ruthenium nanoparticles immobilized on an acidic supported ionic liquid phase (Ru@SILP-SO 3 H) as a multifunctional catalyst. The catalyst components are assembled through a molecular approach ensuring synergistic action of the metal and acid functions. The resulting catalyst is highly active for the hydrogenolysis of various diaryl ethers. For symmetric substrates such as diphenyl ether, hydrogenolysis is followed by full hydrodeoxygenation producing the corresponding cycloalkanes as the main products. For unsymmetric substrates, the cleavage of the C-O bond is regioselective and occurs adjacent to the unsubstituted phenyl ring. As hydrogenation of benzene is faster than hydrodeoxygenation over the Ru@SILP-SO 3 H catalyst, controlled mixtures of cyclohexane and substituted phenols are accessible with good selectivity. Application of Ru@SILP-SO 3 H catalyst in continuous-flow hydrogenolysis of 2-methoxy-4-methylphenoxybenzene is demonstrated with use of commercial equipment.
- Rengshausen, Simon,Etscheidt, Fabian,Gro?kurth, Johannes,Luska, Kylie L.,Bordet, Alexis,Leitner, Walter
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p. 405 - 412
(2019/02/26)
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- INDOLINE DERIVATIVES
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Compounds of Formula (I) are disclosed and methods of treating viral infections with compositions comprising such compounds.
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Page/Page column 97
(2018/02/28)
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- Tuning the Reactivity of Peroxo Anhydrides for Aromatic C-H Bond Oxidation
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Phenol moieties are key structural motifs in many areas of chemical research from polymers to pharmaceuticals. Herein, we report on the design and use of a structurally demanding cyclic peroxide (spiro[bicyclo[2.2.1]heptane-2,4′-[1,2]dioxolane]-3′,5′-dione, P4) for the direct hydroxylation of aromatic substrates. The new peroxide benefits from high thermal stability and can be synthesized from readily available starting materials. The aromatic C-H oxidation using P4 exhibits generally good yields (up to 96%) and appreciable regioselectivities.
- Pilevar, Afsaneh,Hosseini, Abolfazl,?ekutor, Marina,Hausmann, Heike,Becker, Jonathan,Turke, Kevin,Schreiner, Peter R.
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p. 10070 - 10079
(2018/09/06)
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- CYCLIC PEROXIDE OXIDATION OF AROMATIC COMPOUND PRODUCTION AND USE THEREOF
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The present invention provides a method for converting an aromatic hydrocarbon to a phenol by providing an aromatic hydrocarbon comprising one or more aromatic C-H bonds and one or more activated C-H bonds in a solvent; adding a phthaloyl peroxide to the solvent; converting the phthaloyl peroxide to a di-radical; contacting the di-radical with the one or more aromatic C-H bonds; oxidizing selectively one of the one or more aromatic C-H bonds in preference to the one or more activated C-H bonds; adding a hydroxyl group to the one of the one or more aromatic C-H bonds to form one or more phenols; and purifying the one or more phenols.
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Page/Page column 9; 10
(2014/10/15)
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- An alternative procedure for the synthesis of 1,8-dimethyl-5- methoxytetralin-6-ol
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The commercially available 3-hydroxy-4-methoxy-benzaldehyde 3 was subjected to hydrogenation and protection to give the methoxy methyl ether of 2-methoxy-5-methylphenol. This was converted to 1,8-dimethyl-5-methoxytetralin- 6-ol by alkylation with 5-bromopent-1-ene, cyclisation and deprotection.
- Banerjee, Ajoy K.,Poon, Po S.,Bedoya, Liadis
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p. 309 - 310
(2013/07/27)
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- Metal-free oxidation of aromatic carbon-hydrogen bonds through a reverse-rebound mechanism
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Methods for carbon-hydrogen (C-H) bond oxidation have a fundamental role in synthetic organic chemistry, providing functionality that is required in the final target molecule or facilitating subsequent chemical transformations. Several approaches to oxidizing aliphatic C-H bonds have been described, drastically simplifying the synthesis of complex molecules. However, the selective oxidation of aromatic C-H bonds under mild conditions, especially in the context of substituted arenes with diverse functional groups, remains a challenge. The direct hydroxylation of arenes was initially achieved through the use of strong Bronsted or Lewis acids to mediate electrophilic aromatic substitution reactions with super-stoichiometric equivalents of oxidants, significantly limiting the scope of the reaction. Because the products of these reactions are more reactive than the starting materials, over-oxidation is frequently a competitive process. Transition-metal-catalysed C-H oxidation of arenes with or without directing groups has been developed, improving on the acid-mediated process; however, precious metals are required. Here we demonstrate that phthaloyl peroxide functions as a selective oxidant for the transformation of arenes to phenols under mild conditions. Although the reaction proceeds through a radical mechanism, aromatic C-H bonds are selectively oxidized in preference to activated-H bonds. Notably, a wide array of functional groups are compatible with this reaction, and this method is therefore well suited for late-stage transformations of advanced synthetic intermediates. Quantum mechanical calculations indicate that this transformation proceeds through a novel addition-abstraction mechanism, a kind of 'reverse-rebound' mechanism as distinct from the common oxygen-rebound mechanism observed for metal-oxo oxidants. These calculations also identify the origins of the experimentally observed aryl selectivity.
- Yuan, Changxia,Liang, Yong,Hernandez, Taylor,Berriochoa, Adrian,Houk, Kendall N.,Siegel, Dionicio
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p. 192 - 196
(2013/08/23)
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- Exploratory studies towards a total synthesis of the unusual bridged tetracyclic Lycopodium alkaloid lycopladine H
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A strategy for a total synthesis of the structurally novel Lycopodium alkaloid lycopladine H has been investigated. Key steps that have been tested include: 1. a regioselective DielseAlder cycloaddition of nitroethylene with an o-quinone ketal to produce the bicyclo[2.2.2]octane moiety of the alkaloid; 2. a stereoselective Henry reaction to generate the requisite functionality and configuration at C-5; 3. a stereoselective catalytic hydrogenation of a trisubstituted alkene to set the C-15 methyl configuration.
- Sacher, Joshua R.,Weinreb, Steven M.
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p. 10203 - 10207
(2012/10/29)
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- Compounds that modulate PPAR activity and methods of preparation
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This invention discloses compounds that alter PPAR activity. The invention also discloses pharmaceutically acceptable salts of the compounds, pharmaceutically acceptable compositions comprising the compounds or their salts, and methods of using them as therapeutic agents for treating or preventing hyperlipidemia and hypercholesteremia in a mammal. The present invention also discloses methods for making the disclosed compounds.
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- Intermolecular Diels-Alder reactions of brominated masked o-benzoquinones with electron-deficient dienophiles. A detour method to synthesize bicyclo[2.2.2]octenones from 2-methoxyphenols
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Intermolecular Diels-Alder reactions of masked o-benzoquinones, i.e., 6,6-dimethoxy-2,4-cyclohexadienones 5-7 and 21-24 generated from 2-methoxyphenols 1-3 and 17-20, respectively, with electron-deficient dienophiles leading to highly functionalized bicyclo[2.2.2]octenones are described. The masked o-benzoquinones (MOBs) 5-7 underwent Diels-Alder cycloadditions with methyl acrylate, methyl methacrylate, and methyl vinyl ketone to provide bicyclo[2.2.2]octenones 13a-c to 15a-c (direct method) in low to moderate yields with the concomitant formation of considerable amounts of dimers 9-11. To retard dimerization and to improve the yields of the requisite bicyclo[2.2.2]octenones, a detour method comprised of sequential bromination of 2-methoxyphenols 1-4, oxidation and Diels-Alder reaction, and debromination has been developed. The oxidation of bromophenols 17-20 produced MOBs 21-24 which are stable enough to be isolated. The MOBs 21-24 underwent cycloaddition with electron-deficient dienophiles in a very efficient manner to afford the corresponding cycloadducts 25a-c to 28a-c in good to high yields without self-dimerization. When the cycloadducts 25a-c to 28a-c were treated with either Bu3SnH/AIBN or tributylammonium formate-palladium reagent, the corresponding debrominated products 13a-c to 16a-c were obtained in high to excellent yields. In general, the cycloadducts 13a-c to 15a-c were obtained in 20-40% higher yields via the detour method than those via the direct method. In both routes, the Diels-Alder reactions proceeded in a highly regio- and stereoselective manner to furnish a single cycloadduct in each case.
- Lai, Chien-Hsun,Shen, Yi-Ling,Wang, Min-Nen,Rao, N. S. Kameswara,Liao, Chun-Chen
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p. 6493 - 6502
(2007/10/03)
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- The Huang-Minlon modification of Wolff-Kishner reduction in rapid and simple way using microwave technology
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A high yielding, simple and fast method for the reduction of various aldehydes and ketones to the respective hydrocarbons following Huang-Minlon modification tender microwave irradiation is described.
- Chattopadhyay, Sarmishtha,Banerjee, Sajal Kumar,Mitra, Alok Kumar
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p. 906 - 907
(2007/10/03)
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- Reactivity in cleavage of dimethoxybenzenes by sodium in liquid ammonia
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The sodium/liquid ammonia cleavage of the dimethoxybenzenes and related substances, reported in large part by Birch in 1947, has been re-examined with use of improved techniques. Remarkable patterns of reactivity (e.g., ortho > meta ? para) that he described are confirmed and extended. They are agreeably rationalized by means of a simple, approximate adaptation from MO theory.
- Bunnett, Joseph F.,Jenvey, Judy
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p. 8069 - 8073
(2007/10/03)
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- The Photo-Fries Rearrangement of 2,5-Disubstituted Phenyl Acetates
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In a homogenous solution, the photo-Fries rearrangement of 2,5-disubstituted phenyl acetates gives ortho-hydroxyacetophenones as major photoproducts.The ortho/para ratio can be increased by using a highly viscous medium or restricted spaces such as those in zeolites.On the other hand, micellar solutions have little effect.
- Suau, Rafael,Torres, Gregorio,Valpuesta, Maria
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p. 1311 - 1314
(2007/10/02)
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- New Synthesis of 2-Alkoxy-5-methyl-1,4-benzoquinones by the Oxidation of 4-Methylcatechol with Copper (II) Chloride in Alcohols
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4-Methylcatechol was oxidized with copper (II) chloride in various alcohols under oxygen to give the corresponding 2-alkoxy-5-methyl-1,4-benzoquinones.
- Takizawa, Yasuomi,Iwasa, Yoshihito,Suzuki, Toshiaki,Miyaji, Hiroyuki
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p. 1863 - 1864
(2007/10/02)
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- Isomeric Monomethyl Ether Derivatives of (RS)-9,10-Dihydroxyaporphine ("Isoapomorphine") as Possible Products of Metabolism by Catechol-O-methyltransferase
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The isomeric monomethyl ether derivatives of (RS)-9,10-dihydroxyaporphine ("isoapomorphine") were synthesized unequivocally as possible metabolites in catechol-O-methyltransferase (COMT) mediated O-methylation reactions.In vitro incubation studies revealed that isoapomorphine is not a substrate for the COMT using experimental conditions under which apomorphine (10,11-dihydroxyaporphine) is converted in high yield into its 10-methyl ether, apocodeine.The in vivo dopaminergic inactivity of isoapomorphine (as compared with that of apomorphine) seems to be due to factors other than metabolic inactivation by COMT.
- Cannon, Joseph G.,Qijie, Pang
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p. 1079 - 1082
(2007/10/02)
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- REDUCTION WITH METAL BOROHYDRIDE-TRANSITION METAL SALT SYSTEM. II. REDUCTION OF BENZYL ACETATES TO HYDROCARBONS WITH SODIUM BOROHYDRIDE-NICKEL(II) CHLORIDE
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Reductive cleavage of benzyl acetates selectively with nickel boride yielding corresponding hydrocarbons is described.
- He, Yun,Pan, Xinfu,Zhao, He,Wang, Shaofei
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p. 3051 - 3054
(2007/10/02)
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- Tobacco smoke chemistry. 2. Alkyl and alkenyl substituted guaiacols found in cigarette smoke condensate.
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A series of alkyl and alkenyl substituted guaiacols, which comprise a group of biologically and organoleptically active compounds, have been synthesized. Mass spectra and GC retention times for these have been recorded and compared with those obtained for constituents of a weakly acidic fraction of smoke condensate derived from American blend type cigarettes. On the basis of these results, 25 guaiacols have been identified, 18 of which have not been detected in tobacco smoke condensate previously.
- Arnarp,Bielawski,Dahlin,Dahlman,Enzell,Pettersson
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- Natural Benzofurans. Synthesis of Moracin A and B
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2-(3,5-Dihydroxyphenyl)-4,6-dimethoxybenzofuran (Moracin A) and 2-(3-hydroxy-5-methoxyphenyl)-5-hydroxy-6-methoxybenzofuran (Moracin B), phytoalexins isolated from diseased mulberry have been synthesized by short routes in which the benzofuran heterocyclic system is formed by an intramolecular Wittig reaction.
- Burke, John M.,Stevenson, Robert
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p. 451 - 466
(2007/10/02)
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- Evidence against 1,2-Migrations in Aryl Cations
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Photolytic methoxydediazoniation of 2-diazo-4-methylphenol (1) and 2-diazo-5-methylphenol (2) in 50percent CH3OH-H2SO4 yielded 2-methoxy-4-methylphenol (creosol) and 2-methoxy-5-methylphenol (isocreosol), respectively.The absence of detectable amounts of crossover products (within the limits of detection of 5percent) in both reactions demonstrates that no 1,2-hydroxyl shift occured in the intermediate phenylium ion nor could the hypothetical protonated benzoxirene be an intermediate in this reaction.
- Haberfield, Paul,Cardona, Claudia,Bell, Mark
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- Isolement du prestegane B a partir de Steganotaenia araliacea Hochst., premier lignane bis-(meta-hydroxy-benzyl)-butanolide d'origine vegetale. - Isolement et synthese en une etape du dimethylmatairesinol -
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Prestegane B -the first higher plant occured dibenzyl butanolide lignan with two meta-phenols- and its dimethylether were isolated from S. araliacea and the structure deteminations were performed with the aid of high resolution NMR and Mass fragmentation for the former, and with 2-D J resolved 1H NMR studies and synthesis for the latter.
- Taafrout, M.,Rouessac, F.,Robin, J.-P.,Davoust, D.
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p. 4127 - 4128
(2007/10/02)
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- Dihydrostilbenes of Cannabis. Synthesis of Canniprene
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Canniprene (10) is synthesised via reaction of a phenolate-anion ylide with a benzyl-protected aldehyde.Benzoylation, followed by hydrogenation and hydrogenolysis of the resulting stilbene, leads to a half-benzoylated bibenzyl which is converted into its O-dimethylprop-2-ynyl derivative.Semi-hydrogenation, Claisen rearrangement, and debenzoylation gives canniprene.In a second synthesis the prenylated (3-methylbut-2-enylated) and benzyl-protected ring-B section is made first and converted by Wittig reaction into a dibenzyl-protected stilbene.The stilbene is reduced and the benzyl groups removed in one step, without affecting the prenyl group, by sodium in butanol: magnesium in methanol is capable of stilbene reduction without debenzylation.This practical synthesis proceeds in 19 percent overall yield from the dimethylprop-2-ynyl ether of isovanillin (14) and is applicable to isotopelabelling.The use of p-bromophenacyl (PBP) ether and methoxyethoxymethyl (MEM) ether protection as the basis for canniprene synthesis is also considered.Other bibenzyls relevant to the natural products of Cannabis are made and the methylated chroman (37) derived from canniprene is also synthesised.
- Crombie, Leslie,Jamieson, Sally V.
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p. 1467 - 1476
(2007/10/02)
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- Process for preparing hydroxyphenyl ethers
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A process for preparing hydroxyphenyl ethers by oxidizing phenyl ethers with hydrogen peroxide in the presence of a ketone or with a ketone peroxide.
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- Method for manufacture of dihydric phenols
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Dihydric phenols are produced preferentially in high yields by having monohydric phenols or phenyl ethers oxidized by an organic peracid using, as a catalyst, at least one member selected from the group consisting of peracid stabilizers, polycarboxylic acids containing N or OH and possessed of a structure from which heavy metal ion-chelating property can theoretically be assumed, magnesium salts, sodium salts and potassium salts thereof, sodium salt, potassium salt and lower alkyl esters of phosphoric acid, and sodium salt and lower alkyl esters of pyrophosphoric acid.
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