cas 642-71-7, 3,4,5-Trimethoxyphenol | Articles data

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Articles about 642-71-7Total 35 be found

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In vitro antiplasmodial activity of extracts of tristaniopsis species and identification of the active constituents: Ellagic acid and 3,4,5-trimethoxyphenyl-(6'-O-galloyl)-O-/?-D-glucopyranoside
Screening of plants from New Caledonia for antiplasmodial activity against Plasmodium falciparum revealed that methanolic extracts of the leaves and bark of Tristaniopsis calobuxus, T. yateensis, and T. glauca inhibited the growth of chloroquine-sensitive and -resistant clones. Ellagic acid and the new compound 3,4,5-trimethoxyphenyl-(6'-O-galloyl)-O-β-D-glucopyranoside were identified as the active constituents (ICso 0.5 and 3.2 /M, respectively). The growth inhibition of both clones was comparable. The compounds showed negligible or very low cytotoxicity to human skin fibroblasts and Hep G2 cells when tested at concentrations ranging from 0.5 to 100 πM.
Verotta, Luisella,Dell'Agli, Mario,Giolitot, Andrea,Guerrini, Marco,Cabalion, Pierre,Bosisio, Enrica
p. 603 - 607
(2001)
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Benzophenone Glucosides and B-Type Proanthocyanidin Dimers from Zambian Cassia abbreviata and Their Trypanocidal Activities
Two benzophenone glucosides (1 and 2), five flavan-3-ol dimers (5–9), and 17 known compounds (3, 4, and 10–24) were identified from the bark extract of Cassia abbreviata. The chemical structures display two points of interest. First, as an unusual charact
Choongo, Kennedy,Ishikawa, Yoshinobu,Kikuchi, Takashi,Munsimbwe, Linous,Murata, Toshihiro,Shirakura, Izumi,Suganuma, Keisuke
p. 91 - 104
(2022/01/20)

Synthesis and anti-proliferative activities of 5,6,7-trimethoxyflavones and their derivatives
A series of 5,6,7-trimethoxyflavones 1a-1g and their derivatives 2a-2g, 3a-3d, 4 and 5, including the natural products 5,6,7-trimethoxy-4’-hydroxyflavone (1a), 5,6,7,3’,4’ -pentamethoxyflavone (sinensetin, 1 b), 5,6,7-trimethoxy-3’,4’-methyl enedioxy flavone (1c), 5,6,7,3’-tetramethoxy-4,5’-methylenedioxyflavone (1e), 5,6,7, 3’,4’,5’-hextamethoxyflavone (1 g), 5-hydroxy-3,4,2’,3’,4’-pentamethoxy chal-cone (2 b), 5,4’-dihydroxy-6,7-dimethoxy flavone (cirsimaritin, 3a) and 5-hydroxy-6,7,3’, 4’-tetramethoxyflavone (5-demethylsinensetin, 3 b), 3,5,6,7,3’,4’-hexamethoxyflavone (3-methoxysinensetin, 4) and 5’-hydroxy-3,6,7,3’,4’-pentamethoxyflavone (5) were synthesized. Their anti-proliferative activity in?vitro was evaluated against a panel of four human cancer cell lines (Aspc-1, HCT-116, HepG-2 and SUN-5) by the CTG assay. The results showed that most of the synthetic compounds exhibited moderate to high anti-proliferative activities. In particular, compound 3c possess IC50 (5.30 μM) values below 10 μM against Aspc-1 cells and are worthy of further investigation.
Li, Wei,Liu, Kexiong,Su, Liang,Wang, Qiuan
supporting information

(2021/08/12)

Rongalite-promoted metal-free aerobic ipso-hydroxylation of arylboronic acids under sunlight: DFT mechanistic studies
A novel rongalite-promoted metal-free aerobic ipso-hydroxylation of arylboronic acids has been developed. This method employs low-cost rongalite as a radical initiator and O2 as a green oxidizing agent for ipso-hydroxylation. This protocol is compatible with a wide variety of functional groups with good to excellent yields at room temperature. Furthermore, mechanistic insight into the role of superoxide radical anions in C-B cleavage has also been provided based on DFT studies.
Golla, Sivaparwathi,Poshala, Soumya,Pawar, Ravinder,Kokatla, Hari Prasad
supporting information

(2019/12/27)

A convenient synthesis of phenols
Anilines are rapidly, often within 60 minutes, converted into the corresponding phenols in up to 87% isolated yield. The presented experimentally simple protocol display broad compatibility with a variety of functional groups, and in particular, well suited for the preparation of methyl-substituted phenols. Such phenols are not easily available by other synthetic approaches. The formation of phenolic radical coupling products was not observed even for activated anilines using this open flask method.
Kristianslund, Renate,Vik, Anders,Hansen, Trond V.
supporting information
p. 2809 - 2814
(2018/12/04)

Accessing Polyoxygenated Dibenzofurans via the Union of Phenols and o-Benzoquinones: Rapid Syntheses of Metabolites Isolated from Ribes takare
The construction of polyoxygenated dibenzo[b,d]furan frameworks from the union of substituted phenols/naphthols and o-benzoquinones via a Michael-oxidation-oxa-Michael cascade is reported. The power of this transformation is demonstrated in the generation of a library of highly substituted dibenzofurans, featuring specifically substituted molecules containing broad ranges of functionality. The utility of this method is showcased in the total syntheses of two dibenzofurans isolated from Ribes takare, assembling the carbon scaffold of both natural products in one operation.
Zhang, Meng Yao,Barrow, Russell A.
supporting information
p. 2302 - 2305
(2017/05/12)

Ga(OTf)3-mediated synthesis of substituted benzofurans
A synthetic procedure, for the synthesis of a series of functionalized benzofurans 3–5 and benzonaphthofurans 6, starting from intermolecular O-alkylation of α-bromoaryl ketones 2 with potassium oxygenated phenoxides 1 followed by Ga(OTf)3-catalyzed direct intramolecular cyclodehydration of the resulting α-aryloxyaryl ketones, has been developed. The use of various metal triflates was investigated for a facile approach and efficient transformation. Pentacyclic benzophenanthrofurans 7 were prepared via photolytic annulations of 5.
Wang, Heui-Sin,Chan, Chieh-Kai,Chang, Meng-Yang
p. 5132 - 5141
(2016/07/25)

Two new glycosides from Duboscia macrocarpa Bocq.
Two new compounds namely dubosciasides A (1) and B (2) were isolated from stem bark of Duboscia macrocarpa Bocq. together with three known flavonoids. Their structures were determined by spectroscopic methods including one- and two-dimensional NMR, EIMS and HRESIMS. The new compounds were identified as 6-C-β-d-apiofuranosyl-(1 → 4)-β-d-galactopyranosylnaringetol (1) and 1-O-α-l-rhamnopyranosyl-(1 → 4)-β-d-xylopyranosyl-3,4,5-trimethoxyphenol (2).
Tchuendem, Marguerite H.K.,Douanla, Pascal D.,Tabopda, Turibio K.,Tchinda, Alembert T.,Tamze, Véronique,Nkengfack, Augustin E.,Abegaz, Berhanu M.,Connolly, Joseph D.
p. 1 - 4
(2014/12/10)

Palladium-catalyzed hydroxylation of aryl and heteroaryl halides enabled by the use of a palladacycle precatalyst
A method for the hydroxylation of aryl and heteroaryl halides, promoted by a catalyst based on a biarylphosphine ligand tBuBrettPhos (L5) and its corresponding palladium precatalyst (1), is described. The reactions allow the cross-coupling of both potassium and cesium hydroxides with (hetero)aryl halides to afford a variety of phenols and hydroxylated heteroarenes in high to excellent yield.
Cheung, Chi Wai,Buchwald, Stephen L.
p. 5351 - 5358
(2014/06/23)

An alternate preparation of 3,4,5-trimethoxyphenol
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Qin, Qi-Xue,Yang, Jian,Chen, Duo-Zhi,Yang, Bo,Zhang, Ji
p. 321 - 324
(2013/07/26)

Synthesis of polyalkoxy-3-(4-methoxyphenyl)coumarins with antimitotic activity from plant allylpolyalkoxybenzenes
Novel polyalkoxy-3-(4-methoxyphenyl)coumarins - analogues of natural antimitotic compounds - were synthesized from plant allylpolyalkoxybenzenes and tested in vivo in the phenotypic sea urchin embryo assay for antiproliferative antitubulin activity.
Tsyganov, Dmitry V.,Chernysheva, Natalia B.,Salamandra, Lev K.,Konyushkin, Leonid D.,Atamanenko, Olga P.,Semenova, Marina N.,Semenov, Victor V.
p. 147 - 149
(2013/07/26)

Synthesis of polyhydroxylated flavonoids bearing a lipophilic decyl tail as potential therapeutic antioxidants
Antioxidants have potential for the treatment of stroke and neurodegeneration, and chimeric compounds that combine a flavon-3-ol head group related to myricetin and a lipophilic decyl tail are known to protect membranes from oxidative damage at least as well as vitamin E. New flavon-3-ols that are highly hydroxylated in the B ring in ways not found in natural flavon-3-ols and bearing a lipophilic decyl tail have been prepared from trimethoxy-and tetramethoxybenzoic acids accessed by lithiation-carboxylation reactions. Direct enolate acylation was preferred over Baker-Venkataraman rearrangement when there were methoxy groups at both the 2-and the 6-position of the benzoic acid derivatives.
Caldwell, Stuart T.,McPhail, Donald B.,Duthie, Garry G.,Hartley, Richard C.
scheme or table
p. 23 - 33
(2012/03/07)

Enantioselective α-hydroxylation of β-keto esters catalyzed by chiral S-timolol derivatives
A screen of aryloxy aminopropanol organocatalysts derived from the β-blocker inhibitor S-timolol determined the most active catalyst of asymmetric α-hydroxylation of β-keto esters. (R)-1-(tert-butylamino)- 3-(3,4,5-trimethoxyphenoxy) propan-2-ol (3k) was the most effective derivative, enantioselectively catalyzing α-hydroxylation of β-keto esters using tert-butyl hydroperoxide as the oxidant in hexane to afford the corresponding products in excellent yield and with good enantioselectivity (up to 96% yield, 88% ee).
Cai, Yuanchun,Lian, Mingming,Li, Zhi,Meng, Qingwei
scheme or table
p. 7973 - 7977
(2012/09/21)

COGNITIVE DISORDER-AMELIORATING AGENT
A cognitive impairment ameliorant is provided that is useful for the prevention or treatment of cognitive impairment, and particularly Alzheimer's disease. The cognitive impairment ameliorant contains royal jelly as an active ingredient thereof.
-
(2011/05/04)

A simple and efficient asymmetric synthesis of anxiolytic drug enciprazine
A straightforward and efficient asymmetric synthesis of (S)-1-[4-(2-methoxyphenyl)piperazin-1-yl]-3-(3,4,5-trimethoxyphenoxy) propan-2-ol is described. The key intermediate, (S)-2-[(3,4,5-trimethoxyphenoxy) methyl]oxirane, was obtained by a hydrolytic kinetic resolution method using the catalyst (R,R)-salen-cobalt(III) complex. Georg Thieme Verlag Stuttgart.
Narsaiah, A. Venkat,Nagaiah
experimental part
p. 2705 - 2707
(2010/10/18)

Preparation of two sets of 5,6,7-trioxygenated dihydroflavonol derivatives as free radical scavengers and neuronal cell protectors to oxidative damage
An unusual class of 5,6,7-trioxygenated dihydroflavonols (3a-e and 4a-j) were designed and prepared. Their antioxidative properties were assessed by examining their capacities in several in vitro models, including superoxide anion and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, rat liver homogenate lipid peroxidation inhibition, PC12 cells protection from oxidative damage, and xanthine oxidase inhibition. These dihydroflavonols displayed positive quenching abilities towards O2{radical dot} - and DPPH free radicals, in which the majority exhibited superior antioxidant properties to Vitamin C. cis-Configurated compound (±)-3e demonstrated remarkable inhibition to LPO with an IC50 value of 1.9 ± 0.3 μM, which was apparently stronger than that of quercetin (IC50 = 6.0 ± 0.4 μM). trans-Configurated dihydroflavonol (±)-4h exhibited significant protective effect on PC12 cells against oxidative damage with an EC50 value of 41.5 ± 5.3 μM, more effective compared to that of quercetin (EC50 = 81.8 ± 8.7 μM). The 6-OH-5,7-dimethoxy analogue (±)-3d showed significant inhibition of xanthine oxidase with an IC50 value of 16.0 ± 0.8 μM, which is superior to that of allopurinol (IC50 = 23.5 ± 2.0 μM). In addition to the hypothesized action mechanism of the bio-active compounds, 3D modeling was used to analyze the relationship between the minimized-energy structures and antioxidant activities.
Gong, Jingxu,Huang, Kexin,Wang, Feng,Yang, Leixiang,Feng, Yubing,Li, Haibo,Li, Xiaokun,Zeng, Su,Wu, Xiumei,Stoeckigt, Joachim,Zhao, Yu,Qu, Jia
supporting information; experimental part
p. 3414 - 3425
(2009/09/27)

Tuning the polarization along linear polyaromatic strands for rationally inducing mesomorphism in lanthanide nitrate complexes
The opposite orientation of the ester spacers in the rodlike ligands L4C12 (benzimidazole-OOC-phenyl) and L5C12 (benzimidazole-COO-phenyl) drastically changes the electronic structure of the aromatic systems, without affecting their meridional Incoordination to trivalent lanthanides, Ln111, and their thermotropic liquid crystalline (i.e., mesomorphic) behaviors. However, the rich mesomorphism exhibited by the complexes [Ln(L4C12)-(NO3)3] (Ln = La-Lu) vanishes in [Ln-(L5C12)(NO3)3], despite superimposable molecular structures and comparable photophysical properties. Density functional theory (DFT) and time-dependant DFT calculations performed in the gas phase show that the inversion of the ester spacers has considerable effects on the electronic structure and polarization of the aromatic groups along the strands, which control residual intermolecular interactions responsible for the formation of thermotropic liquid-crystalline phases. As a rule of thumb, an alternation of electron-poor and electron-rich aromatic rings favors intermolecular interactions between the rigid cores and consequently mesomorphism, a situation encountered for L4C12, L5C12, [Ln(L4C12)(NO3)3], but not for [Ln(L5 C12)(NO3)3]. The intercalation of an additional electron-rich diphenol ring on going from [Ln(L5C12)-(NO 3)3] to [Ln(L6C12)(NO3)3] restores mesomorphism despite an unfavorable orientation of the ester spacers, in agreement with our simple predictive model.
Terazzi, Emmanuel,Guenee, Laure,Morgantini, Pierre-Yves,Bernardinelli, Gerald,Donnio, Bertrand,Guillon, Daniel,Piguet, Claude
p. 1674 - 1691
(2008/02/04)

Mechanistic study of a Pd/C-catalyzed reduction of aryl sulfonates using the Mg-MeOH-NH4OAc system
A method for the deoxygenation of phenolic hydroxy groups via aryl triflates or mesylates has been established by using a combination of Pd/ C-Mg-MeOH. The addition of NH4OAc to the system markedly accelerated the reaction rate and expanded the scope of the reaction. Mechanistic studies suggested that a single-electron transfer process from the Pd0 center to the benzene ring is involved in the reduction of aryl sulfonates and that NH4OAc works as a solubilization re agent of the Mg salt and as an accelerator of the electron transfer, thus enhancing the reaction process. Our method was also applicable to the regioselective deuteration of benzene derivatives with CH3OD as the solvent and deuterium source: the original hydroxy group could be efficiently replaced with a deuterium atom.
Mori, Akinori,Mizusaki, Tomoteru,Ikawa, Takashi,Maegawa, Tomohiro,Monguchi, Yasunari,Sajiki, Hironao
p. 1432 - 1441
(2008/02/04)

PROCESS FOR PREPARING ALKOXY- AND ARYLOXY-PHENOLS
Process for preparing alkoxy- and aryloxy-phenols, comprising oxidizing the ketone of formula (I) with peracids to give the corresponding ester of formula (II) which is then hydrolysed to give the corresponding aryloxy- or alkoxy-phenol.
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Page 12

(2008/06/13)

Indole derivatives with vascular damaging activity
The invention provides a compound of Formula (I) wherein: R1 and R2 are independently selected from hydrogen, halogen, —CN, a hydrocarbyl group or a group of Formula (II); wherein W is aryl or a heterocyclic group, R4 is independently select from hydrogen, halogen, —OH, amino, alkanoylamino, —OPO3H2, or a hydrocarbyl group, wherein the amino group is optionally substituted by an amino acid residue and the hydroxy group is optionally esterified or two R4 groups together form an optionally substituted cyclic or heterocyclic group; X is selected from Μ(y) S+—, +—O—+, —+S(O)+—, —+S(O2)+— and —+NH—; p is an integer from 0 to 4; and q is an integer from 1 to 4; R3 and R10 are independently selected from hydrogen, lower alkyl or a group of Formula (IV): wherein Y is selected from +NH+—, —Μ(Y)OΜ(Y)— or a bond; Z is selected from +NH+—, —+Oν—, —+C(O)+— or a bond; r is an integer from 0 to 4; t is an integer from 0 to 1; R6 is hydrogen, a hydrocarbyl group or a group of Formula (V): wherein n is an integer of from 1 to 6, and; R7 and R8 are independently selected from hydrogen or a hydrocarbyl group; and R11 is hydrogen or lower alkyl; or a salt or solvate thereof; provided that: I) when R1 is an unsubstituted phenylthio group (Ph—S—), R2 is H, R10 is H and R11 is H then R3 is neither H nor —C(O)—O—CH2CH3; and ii) R1, R2 and R3 are not all hydrogen. Such compounds are predicted to cause the selective destruction of tumour vasculature. They may therefore be used to inhibit and/or reverse, and/or alleviate symptoms of angiogenesis and/or any disease state associated with angiogenesis.
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(2008/06/13)

Selenium catalysed oxidations with aqueous hydrogen peroxide. Part 3: Oxidation of carbonyl compounds under mono/bi/triphasic conditions
The total synthesis of 3,5-bis(perfluorooctyl)phenyl butylselenide (1), a recyclable catalyst for oxidation reactions with hydrogen peroxide, is described. The catalyst can be used for oxidation of aldehydes and ketones under monophasic, but also fluorous biphasic or fluorous triphasic conditions.
Ten Brink, Gerd-Jan,Vis, J.Martijn,Arends, Isabel W.C.E,Sheldon, Roger A
p. 3977 - 3983
(2007/10/03)

Selenium-catalyzed oxidations with aqueous hydrogen peroxide. 2. Baeyer-Villiger reactions in homogeneous solution
Several diselenides were tested for catalytic activity in Baeyer-Villiger reactions with 60% aqueous hydrogen peroxide. Bis[3,5-bis(trifluoromethyl)phenyl] diselenide forms the corresponding 3,5-bis-(trifluoromethyl)benzene seleninic acid in situ, which is a highly reactive and selective catalyst for the oxidation of carbonyl compounds in 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,2-trifluoroethanol, or dichloromethane.
Ten Brink,Vis,Arends,Sheldon
p. 2429 - 2433
(2007/10/03)

Hydrogen peroxide/boric acid: An efficient system for oxidation of aromatic aldehydes and ketones to phenols
Hydrogen peroxide activated by boric acid in the presence of sulfuric acid has been shown to be an efficient oxidizing system for direct conversion of aromatic aldehydes and ketones to phenols.
Roy, Amrita,Reddy,Mohanta, Pramod K.,Ila,Junjappa
p. 3781 - 3791
(2007/10/03)

Method for the production of alkoxy- and aryloxy-phenols
Alkoxybenzaldehydes and aryloxybenzaldehydes are converted to the corresponding phenols by reacting the benzaldehydes in an organic solvent phase with formic acid and hydrogen peroxide in an aqueous solvent phase to produce the corresponding formate ester. The formate ester is then saponified to produce the corresponding phenol.
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(2008/06/13)

Phenolics from Hypericum geminiflorum
Five new constituents were isolated from the heartwood and roots of Hypericum geminiflorum. The structures were characterized as (2R,3R)- 3,5,7,2',5'-pentahydroxyflavan, 3,5-dimethoxy-4-hydroxy-1-O-β-D-glucoside, 3'-[γ-hydroxymethyl-(Z)-γ-methylally]-2',4',4-trihydroxychalcone 11'-O- ferulate, named gemichalcone A, 3'-[γ-hydroxymethyl-(Z)-γ-methylallyl]- 2',4',4-trihydroxychalcone 11'-O-coumarate, named gemichalcone B, and 3'- [γ-hydroxymethyl-(E)-γ-methylallyl]-2',4',4-trihydroxychalcone 11'-O- coumarate, named isogemichalcone B.
Chung, Mei-Ing,Lai, Mei-Hsun,Yen, Ming-Hong,Wu, Ru-Rong,Lin, Chun-Nan
p. 943 - 947
(2007/10/03)

Synthesis and X-ray structure of 2-(3-methyl-2-butenyl)-3,4,5-trimethoxyphenol: a potent anti-invasive agent against solid tumours.
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Parmar,Gupta,Bisht,Mukherjee,Boll,Errington
p. 558 - 560
(2007/10/03)

Benzopyranones, processes for their preparation and their use
Described are 2H-1-benzopyran-2-ones (coumarin derivates) of general formula (I), STR1 wherein R1 is a hydroxyl group, a lower-alkoxy group, a cycloalkoxy group with 4 to 6 C-atoms or the alkyl- or arylsulphonyloxy group R6 --SO2 O--; R2 and R3, independently of each other, are hydrogen atoms, hydroxyl groups, lower-alkoxy groups or cycloalkoxy groups with 4 to 6 C-atoms; R4 is a hydrogen atom, a lower-alkyl group with 1 to 4 C-atoms or a phenyl group; Y is a nitrogen atom, a CH group or a COH group; R5 is a phenyl, naphtyl, pyridinyl or pyrimidinyl group which may optionally be substituted by one or two C1 -C5 alkyl groups, by one or two halogen atoms, by a halogen and C1 -C5 alkyl together, by perfluoroalkyl with 1 to 3 C-atoms, by C1 -C5 alkoxy, by hydroxy, by methylenedioxy or by nitro; R6 is a lower-alkyl group, a cycloalkyl group with 4 to 6 C-atoms or a phenyl group which may optionally be substituted by one or two C1 -C5 alkyl groups, by one or two halogen atoms, or by perfluoroalkyl with 1 to 3 C-atoms; and n=1 to 4; plus their addition compounds with physiologically tolerated acids. Also described are methods of preparing these compounds, novel intermediates in their preparation and methods of preparing such intermediates. The novel coumarin derivatives described possess a neuroprotective and psychopharmacological action. The invention also concerns pharmaceuticals containing these compounds.
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(2008/06/13)

Preparation of methoxyphenols by oxidation of methoxybenzaldehydes with hydrogen peroxide in presence of p-toluenesulphonic acid
Methoxyphenols have been prepared efficiently from the corresponding methoxybenzaldehydes by oxidation with hydrogen peroxide at room temperature in the presence of p-toluenesulphonic acid in methanol.
Baruah, Robindra N.
p. 1103 - 1104
(2007/10/02)

Sodium perborate: A convenient reagent for benzylic hydroperoxide rearrangement
Sodium perborate in boron trifluoride etherate has been found to be an effective reagent for the hydroperoxide rearrangement of electron rich and highly substituted benzylic tertiary alcohols to phenols in good yields.
Kabalka,Reddy,Narayana
p. 7667 - 7668
(2007/10/02)

Use of the Hammett Correlation and ?+ for Calculation of One-Electron Redox Potentials of Antioxidants
Spectral, acid-base, and redox properties of methoxyphenoxyl radicals were determined in aqueous solutions by pulse radiolysis.Except for 2,6-dimethoxyphenoxyl, with λmax 7 = 0.58 V vs NHE, whereas the effect of meta substitution was minimal for 3,5-dimethoxyphenol, E7 = 0.85 V, yet this was 0.12 V lower than the measured E7 of 0.97 V for unsubstituted phenol.The reduction potential E7 of methoxyphenoxyl radicals satisfies the Hammett correlation using Brown ?+ substituent constants, as do other monosubstituted phenoxyls if the additivity of ?+ values is assumed and the state of protonation of the substituents is taken into consideration.The derived ?+(CH3O)m value of -0.14, in contrast to reported positive values, indicates the contribution of the methoxy group, even in the meta position, to charge delocalization and resonant stabilization of the phenoxyl radical.The contribution of the ring structure to more negative ?+ values was observed, as expected.Use of the Hammett correlation is suggested for rapid estimation and accurate calculation of the redox potentials of polysubstituted phenolic antioxidants.
Jovanovic, Slobodan V.,Tosic, Mihajilo,Simic, Michael G.
p. 10824 - 10827
(2007/10/02)

FURTHER POLYSUBSTITUTED FLAVONES FROM AGERATUM HOUSTONIANUM
The aerial parts of Ageratum houstonianum afforded three new flavones, 5-hydroxy-6,7,8,2',4',5'-hexamethoxyflavone; 5,2'-dihydroxy-6,7,8,4',5'-pentamethoxyflavone and 5-hydroxy-6,7,2',4',5'-pentamethoxyflavone.The known 5,6,7,3',4',5'-hexamethoxyflavone was also isolated.Structural determinations involved spectral methods and chemical degradations. - Key Word Index: Ageratum houstonianum; Asteraceae; Eupatorieae; heptasubstituted and hexasubstituted flavones; structure determination.
Quijano, Leovigildo,Calderon, Jose S.,Garibay, Frederico Gomez,Escobar, Edgar,Rios, Tirso
p. 2075 - 2078
(2007/10/02)

Benzylic Hydroperoxide Rearrangement: Observations on a Viable and Convenient Alternative to the Baeyer-Villiger Rearrangement
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Boger, Dale L.,Coleman, Robert S.
p. 5436 - 5439
(2007/10/02)

Electro-organic Reactions. Part 18. The Competition between Cleavage at Aryl-Oxygen and at Tetrazol-5-yl-Oxygen Bonds in the Cathodic Reduction of Aryl Tetrazolyl Ethers
5-Aryloxy-1-phenyltetrazoles are cleaved cathodically in a 2 F mol-1 process.Initial electron transfer is to the tetrazole ring and the compounds cleave predominantly at the tetrazolyl-oxygen bond.An exception is 5-(p-cyanophenoxy)-1-phenyltetrazole which undergoes 1 F mol-1 cleavage to 1-phenyltetrazolone and benzonitrile.Competitive electrolysis of pairs of the tetrazolyl ethers, differently substituted in the aryloxy-ring, allows an estimation of relative rates of cleavage.These rates are found to be roughly related to the pKa values of the corresponding phenols.
Akbulut, Ural,Toppare, Levent,Utley, James H. P.
p. 391 - 394
(2007/10/02)

Cleavage of high molecular phlorotannin derivatives from the brown alga Fucus vesiculosus L
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Glombitza,Lentz
p. 3861 - 3866
(2007/10/02)

Copper-catalyzed synthesis of phenol and diaryl ether derivatives: Via hydroxylation of diaryliodoniums
A copper-catalysed hydroxylation of diaryliodoniums to generate phenols and diaryl ethers is reported. This method allows the synthesis of diversely functionalized phenols under mild reaction conditions without the need for a strong inorganic base or an expensive noble-metal catalyst. Significantly, convenient application of diaryliodoniums is demonstrated in the preparation of diaryl ethers in a one-pot operation.
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(2019/07/22)