- Stable isotope characterization of raspberry ketone extracted from Taxus baccata and obtained by oxidation of the accompanying alcohol (betuligenol)
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The natural abundance 2H NMR characterization of raspberry ketone 1 extracted from himalayan Taxus baccata and of the accompanying (R) carbinol 2 is performed and compared with that of samples of 1 obtained from 2 by oxidation with Candida boidinii and CrO3, respectively. The determination of the δ(13C) and/or δ(18O) values of the above extractive products and of benzoic acid (6) and 4-butylphenol (10), obtained from natural of synthetic 1, and of 4-phenylbutan-2-ol (8), prepared from extractive 2, allows a description of the labeling pattern of this set of products. A graph of (D/H)3/(D/H)2 vs (D/H)5/(D/H)4 (Figure 3) of the presently examined samples and of those previously characterized in the laboratory, including three commercial samples sold as natural, defines three areas, containing (a) the material of botanical origin and that produced from extractive 2 by biooxidation, (b) those produced by bioreduction of the unsaturated ketone 3, and (c) the synthetic samples.
- Fronza, Giovanni,Fuganti, Claudio,Pedrocchi-Fantoni, Giuseppe,Serra, Stefano,Zucchi, Gioia,Fauhl, Carsten,Guillou, Claude,Reniero, Fabiano
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Read Online
- Selective hydrodeoxygenation of hydroxyacetophenones to ethyl-substituted phenol derivatives using a FeRu?SILP catalyst
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The selective hydrodeoxygenation of hydroxyacetophenone derivatives is achieved opening a versatile pathway for the production of valuable substituted ethylphenols from readily available substrates. Bimetallic iron ruthenium nanoparticles immobilized on an imidazolium-based supported ionic liquid phase (Fe25Ru75?SILP) show high activity and stability for a broad range of substrates without acidic co-catalysts. This journal is
- Bordet, Alexis,Goclik, Lisa,Leitner, Walter,Offner-Marko, Lisa
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supporting information
p. 9509 - 9512
(2020/09/02)
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- Synthesis of 4 - n-alkyl substituted phenol method
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The invention discloses a synthesis method of 4-n-alkyl substituted phenol. Under the catalysis of zinc chloride, aniline and n-alkyl alcohol with the carbon number being 4-30 react in methylbenzene or xylene to obtain the 4-n-alkyl substituted aniline, and then the 4-n-alkyl substituted aniline reacts with sodium nitrite and acid to obtain the 4-n-alkyl substituted phenol. The synthesis method is easy to implement, an intermediate directly enters the next reaction without being separated or purified, and therefore the reaction efficiency is improved. The final product is high in purity and is good in depth of parallelism when reappearing, and technological conditions are suitable for mass production.
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Paragraph 0017-0020
(2018/04/01)
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- Photoredox-Assisted Reductive Cross-Coupling: Mechanistic Insight into Catalytic Aryl-Alkyl Cross-Couplings
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Here, we describe a photoredox-assisted catalytic system for the direct reductive coupling of two carbon electrophiles. Recent advances have shown that nickel catalysts are active toward the coupling of sp3-carbon electrophiles and that well-controlled, light-driven coupling systems are possible. Our system, composed of a nickel catalyst, an iridium photosensitizer, and an amine electron donor, is capable of coupling halocarbons with high yields. Spectroscopic studies support a mechanism where under visible light irradiation the Ir photosensitizer in conjunction with triethanolamine are capable of reducing a nickel catalyst and activating the catalyst toward cross-coupling of carbon electrophiles. The synthetic methodology developed here operates at low 1 mol % catalyst and photosensitizer loadings. The catalytic system also operates without reaction additives such as inorganic salts or bases. A general and effective sp2-sp3 cross-coupling scheme has been achieved that exhibits tolerance to a wide array of functional groups.
- Paul, Avishek,Smith, Mark D.,Vannucci, Aaron K.
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p. 1996 - 2003
(2017/02/26)
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- Synthesis and catalytic activity of monobridged bis(cyclopentadienyl)rhenium carbonyl complexes
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Thermal treatment of three monobridged biscyclopentadienes (C5H5)R(C5H5) [R?=?C(CH3)2 (1), C(CH2)5 (2), Si(CH3)2 (3)] with Re2(CO)10 in refluxing mesitylene gave the corresponding complexes [(η5-C5H4)2R][Re(CO)3]2 [R?=?C(CH3)2 (4), C(C5H10) (5), Si(CH3)2 (6)], which were separated by chromatography, and characterized by elemental analysis, IR, and 1H NMR spectroscopy. The molecular structures of complexes 5 and 6 were characterized by X-ray crystal diffraction analysis and show that both are monobridged bis(cyclopentadienyl)rhenium carbonyl complexes in which the molecule consists of two [(η5-C5H4)Re(CO)3] moieties linked by a single bridge, in which each of the two Re(CO)3 units is coordinated to the cyclopentadienyl ring in an η5 mode. All three of these monobridged bis(cyclopentadienyl)rhenium carbonyl complexes have good catalytic activities in Friedel–Crafts alkylation reactions.
- Li, Zhen,Ma, Zhi-Hong,Wang, Hong,Han, Zhan-Gang,Zheng, Xue-Zhong,Lin, Jin
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p. 647 - 653
(2016/07/29)
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- Sustainable oxidations with air mediated by gallic acid: Potential applicability in the reutilization of grape pomace
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Gallic acid converts atmospheric oxygen into hydrogen peroxide, which is able to oxidize arylboronic acids as a proof of concept of sustainable oxidations. Moreover, tannic acid and grape pomace extract are also able to perform oxidations with air. Therefore this work unleashes an alternative method for reutilization and valorization of bio-wastes rich in tannins.
- Scoccia, Jimena,Perretti, Marcelle D.,Monzón, Diego M.,Crisóstomo, Fernando P.,Martín, Víctor S.,Carrillo, Romen
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supporting information
p. 2647 - 2650
(2016/06/06)
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- Oxidation with air by ascorbate-driven quinone redox cycling
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Transition metal-free oxidation with air at room temperature has been achieved by simply using ascorbate (vitamin C) and catalytic amounts of menadione (vitamin K3). A combination of the mentioned vitamins transforms atmospheric oxygen into hydrogen peroxide, which is able to oxidize arylboronic acids and other chemical moieties. This journal is
- Silveira-Dorta, Gastón,Monzón, Diego M.,Crisóstomo, Fernando P.,Martín, Tomás,Martín, Víctor S.,Carrillo, Romen
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supporting information
p. 7027 - 7030
(2015/04/22)
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- Computational and Experimental Studies of Phthaloyl Peroxide-Mediated Hydroxylation of Arenes Yield a More Reactive Derivative, 4,5-Dichlorophthaloyl Peroxide
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The oxidation of arenes by the reagent phthaloyl peroxide provides a new method for the synthesis of phenols. A new, more reactive arene oxidizing reagent, 4,5-dichlorophthaloyl peroxide, computationally predicted and experimentally determined to possess enhanced reactivity, has expanded the scope of the reaction while maintaining a high level of tolerance for diverse functional groups. The reaction proceeds through a novel "reverse-rebound" mechanism with diradical intermediates. Mechanistic insight was achieved through isolation and characterization of minor byproducts, determination of linear free energy correlations, and computational analysis of substituent effects of arenes, each of which provided additional support for the reaction proceeding through the diradical pathway.
- Camelio, Andrew M.,Liang, Yong,Eliasen, Anders M.,Johnson, Trevor C.,Yuan, Changxia,Schuppe, Alex W.,Houk,Siegel, Dionicio
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p. 8084 - 8095
(2015/09/01)
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- Heterogeneous copper-catalyzed hydroxylation of aryl iodides under air conditions
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In this work, the ligand-free heterogeneous copper Cu-g-C3N 4 was synthesized and used for the hydroxylation of aryl iodides to synthesize phenols using cheap bases. The catalyst was conveniently prepared, air-tolerant, reusable and scalable, and is very efficient for a wide range of substrates. The synthesis of substituted phenols can be carried out under air conditions and has great potential for practical applications. This journal is the Partner Organisations 2014.
- Ding, Guodong,Han, Hongling,Jiang, Tao,Wu, Tianbin,Han, Buxing
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supporting information
p. 9072 - 9075
(2014/08/05)
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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 10
(2014/10/15)
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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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- A chemoselective hydrogenation of the olefinic bond of α,β- unsaturated carbonyl compounds in aqueous medium under microwave irradiation
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A microwave-assisted mild and ecofriendly catalytic transfer hydrogenation process was developed to reduce various α,β-unsaturated carbonyl compounds into the corresponding saturated carbonyl compounds in the presence of silica-supported palladium chloride as catalyst and a combination of MeOH/HCOOH/H2O (1:2:3) as hydrogen source within 22-55 minutes in moderate to excellent yields with 100% chemoselectivity.
- Sharma, Anuj,Kumar, Vinod,Sinha, Arun K.
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p. 354 - 360
(2007/10/03)
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- Dinitroalkyl aromatics polymerization retarders or inhibitors and methods for making and for using same
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A vinyl monomer inhibitor systems is disclosed which includes 2,6-dinitro-4-alkylated phenols and mixtures of 2,6-dinitro-4-alkylated phenols and 2,4-dinitro-6-alkylated phenols as well as vinyl monomer stabilized composition including an effective amount of the inhibitor systems. A method for the preparation and use is also disclosed where phenol is first alkylated under conditions that afford predominately monoalkylated phenols having a high para alkylation preference, followed by nitration of the alkylated phenols to form a dinitrated, monoalkylated product.
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- The reactivity of phosphonic esters in aqueous micellar solutions of cationic surfactants
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The micellar effect of cationic surfactants in alkaline hydrolysis of O-alkyl-O-aryl-chloromethyl phosphonates involves a positive contribution of concentrating the reagents and a negative effect of the micellar environment due to a loss in the activation entropy. The reactivity of substrates in micelles depends on both electronic and hydrophobic characteristics of substituents in the aryl group.
- Shagidullina,Zakharova,Valeeva,Kudryavtseva
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p. 1181 - 1185
(2007/10/03)
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- β1- and β2-adrenoceptor antagonist activity of a series of para- substituted N-isopropylphenoxypropanolamines
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To further explore the structure-activity relationships of β- adrenoceptor (β-AR) antagonists, a series of 25 para-substituted N- isopropylphenoxy-propanolamines were synthesised, nine of which are new compounds. All have been examined for their ability to antagonise β1-ARs in rat atria and β2-ARs in rat trachea. Substitution in the para-position of the phenyl ring is thought to confer β3-specificity and the selectivity of these compounds for the β1-AR ranges from 1.5-234. None of the compounds tested were selective for the β2-AR. Of the 25 compounds studied, 22 had reasonable (pA2 > 7) potencies for the rat β1-AR. Only compound 1 displayed reasonable (pA2 > 7) potency for the rat β2-AR. Twenty two compounds were used as the training set for comparative molecular field analysis (CoMFA) of antagonist potency (pA2) at the rat β1- and β2-ARs. The inclusion of a number of additional physical characteristics improved the QSAR analysis over models derived solely using the CoMFA electrostatic and steric fields. The final models predicted the β1- and β2-AR potency of the compounds in the training set with high accuracy (r2 = 0.93 and 0.86 respectively). The final β1-AR model predicted the β1-potencies of two out of the three test compounds, not included in the training set, with residual PA2 values 2-AR model (residual pA2 values -0.38).
- Louis, Simon N.,Nero, Tracy L.,Iakovidis, Dimitri,Colagrande, Felicia M.,Jackman, Graham P.,Louis, William J.
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p. 919 - 937
(2007/10/03)
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- Synthesis of alcohols via mild oxidation of perfluoroethylstannanes
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Alkaline H2O2 oxidizes perfluoroethyl-substituted stannanes to the corresponding alcohols with retention of configuration.
- Falck,Lai, Jing-Yu,Venkata Ramana,Lee, Sang-Gyeong
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p. 2715 - 2718
(2007/10/03)
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- Metal cation-exchanged montmorillonite (Mn+-mont)-catalysed aromatic alkylation with aldehydes and ketones
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The alkylation of aromatic compounds with aldehydes and ketones in the presence of a variety of metal cation-exchanged montmorillonites (Mn+-mont; Mn+ = Zr4+, Al3+, Fe3+, Zn2+, H+, Na+) has been investigated. Al3+- and Zr4+-Monts are revealed to be effective as catalysts, while no reaction takes place with Na+-mont. Al3+-Mont-catalysed alkylation of phenol with several aldehydes produces mainly or almost solely the corresponding gem-bis(hydroxyphenyl)alkanes (bisphenols) in good yields, while that with several ketones affords selectively the corresponding alkylphenols in moderate to good yields. The alkylation always occurs at the carbonyl carbon without any skeletal rearrangement and the kind of products depends much on the steric hindrance of an electrophilic intermediary carbocation. The alkylation of anisole, veratrole and p-cresol proceeds well, while that of toluene, benzene, chlorobenzene and nitrobenzene scarcely occurs.
- Tateiwa, Jun-Ichi,Hayama, Ei,Nishimura, Takahiro,Uemura, Sakae
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p. 1923 - 1928
(2007/10/03)
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- Tilt Angle Variation as a Function of Chain Length and Temperature in the Smectic C Phases of p,Alkoxyphenyl-p,Alkoxybenzoates
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The variation of the tilt angle with temperature in the smectic C phase has generally been shown to be non-existent or very slow for compounds or mixtures with the nematic-smectic C transition, while in the case of systems with the smectic A-smectic C transition, a relation between the steepness of this variation, near the transition, and the width of the smectic A domain has been observed.In this work, the variation of tilt angle in the smectic C phase is described for p-alkoxyphenyl-p-alkoxybenzoate homologous series, for which the evolution of polymorphism can be controlled systematically, by varying stepwise the length of the aliphatic chains, and for which large domains can be obtained for each type of phase sequence, nematic-, smectic A- and isotropic-smectic C.After completing the discussion made previously on the incidence of chain length on polymorphism, we confirm that the variation of tilt angle with temperature is slowest for compounds with intermediate chain lengths corresponding to the largest smectic A temperature range; this variation becomes continuously steeper when the smectic A domain becomes narrow.In addition, we show that the same description can be extended to the other types of phase sequences, by using the hypothesis of a virtual smectic A-smectic C transition above the observed nematic- or isotropic-smectic C transition.In fact, short chain lengths for homologues with a nematic/smectic C transition, or long chain lengths for homologues with an isotropic/smectic C transition, lead to an increase of the tilt angle at the phase transition and to a decrease of the amplitude of its variation with temperature; in our description, this behaviour corresponds to an increase of the temperature range between the real and virtual transitions.As a consequence, the homologues with very short and very long chain lengths show a quasi temperature-independent tilt angle, while the other homologues present a tilt angle variation similar to that observed for compounds exhibiting a smectic C/smectic A transition.This feature indicates that there is no need to distinguish between different types of smectic C phase.
- Heinrich, B.,Guillon, D.
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- Synthesis, Spectral Data and Extraction of Copper by 1-(2'-Hydroxy-5'-alkylphenyl)-1-alkanone Oximes
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1-(2'-Hydroxy-5'-alkylphenyl)-1-ethanone oximes with a normal alkyl group containing 2 to 12 carbon atoms and 1-(2'-hydroxy-5'-methylphenyl)-1-alkanone oximes containing 1 to 11 carbon atoms in the hydrocarbon chain were synthesized.Spectral data (u.v., i.r., n.m.r. and 13C) of oximes are reported.Four of these oximes were used for copper extraction from acidic solution.The results obtained indicate, that these oximes are better extractants than alkyl derivatives of 2-hydroxybenzophenone oximes.
- Krzyzanowska, Ewa,Olszanowski, A.,Juskowiak, M.
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p. 617 - 630
(2007/10/02)
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- 16-Substituted polyunsaturated hexadecanoic fatty acids
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Sixteen carbon atom carboxylic acids having 16-phenoxy or 16-phenylthio substituents, and 0, 1, or 4 triple bonds, methods of preparing them, and pharmaceutical preparations containing them. These compounds are useful as lipoxygenase inhibitors.
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- Arachidonic acid analogs
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Long chain unsaturated hydrocarbon derivatives, having from 13 to 21 carbon atoms, which are substituted at the 1-position by a phenoxy, phenylthio or a phenyl that bear a carboxylic acid group at the ortho, meta or para positions, and up to 4 carbon-carbon triple bonds, methods of preparing them, and pharmaceutical preparations containing them. These compounds are useful as lipoxygenase inhibitors, and therefore as antiinflammatory agents.
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- Aliphatic Liquid Crystals, 2. Some Nematic Derivatives of all-trans-Perhydrophenanthrene
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A stereoselective synthesis of the all-trans-7-alkylperhydro-2-phenanthrenols 15a-f in 11 steps and 28 liquid crystalline esters 16 of 15a-f are described, additionally some further derivatives of 7-alkylperhydro-2-phenanthrenol.An X-ray structure analysis of ester 16ec is reported.
- Sucrow, Wolfgang,Minas, Hermann,Stegemeyer, Horst,Geschwinder, Peter,Murawski, Hans-Ruediger,Krueger, Carl
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p. 3332 - 3349
(2007/10/02)
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