- Catalytic auto-condensation of 2,4-pentanedione promoted by Sm(III) acetylacetonate: The X-ray structure of a novel complex [Sm(CH3COO)3(H2O)2](H2 O)2
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An efficient one-pot catalytic method to obtain 4,6-dimethyl-2-hydroxyacetophenone (A) is reported, the reaction proceeds via the intermolecular auto-condensation of 2,4-pentanedione using samarium(III) acetylacetonate (Sm(AcAc)3) as promoter. A novel complex [Sm(CH3COO)3(H2O)2](H2 O)2 (I) was isolated from the reaction media. The structure of I was determined by X-ray crystallography showing that the central atom is ennea-coordinated (monocapped square-antiprism geometry). This complex I also shows activity in the named autocondensation reaction.
- Arias, José Luis,Cabrera, Armando,Sharma, Pankaj,Rosas, Noé,García, José Luis,Hernandez
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- Solvothermal modification of magnesium phthalocyanine
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Reactivity of magnesium phthalocyanine (MgPc) in the dry 3,4-lutidine (3,4-lut), in the 3,4-lut/DMSO, in DMSO and in 3,4-lut/acetylacetone (acacH) systems has been investigated. Reaction of MgPc with dry 3,4-lut leads to formation of MgPc(3,4-lut) compoun
- Janczak, Jan
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- The power of solvent in altering the course of photorearrangements
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A clean bifurcation between two important photochemical reactions through competition of a triplet state Type II H-abstraction reaction with a photo-Favorskii rearrangement for (o/p)-hydroxy-o-methylphenacyl esters that depends on the water content of the solvent has been established. The switch from the anhydrous Type II pathway that yields indanones to the aqueous-dependent pathway producing benzofuranones occurs abruptly at low water concentrations (~8%). The surprisingly clean yields suggest that such reactions are synthetically promising.
- Sebej, Peter,Lim, Bum Hee,Park, Bong Ser,Givens, Richard S.,Klan, Petr
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supporting information; experimental part
p. 644 - 647
(2011/04/15)
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- Synthesis of 7-hydroxy-6H-benzo[c]chromen-6-ones based on?a '[3+3] cyclization/domino retro-Michael-aldol-lactonization' strategy
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The TiCl4-mediated [3+3] cyclization of 2,4-bis(trimethylsilyloxy)penta-1,3-diene with 3-silyloxyalk-2-en-1-ones afforded 2-acetylphenols, which were transformed into functionalized chromones. The Me3SiOTf-mediated condensation of the latter with 1,3-bis(silyl enol ethers) and subsequent domino 'retro-Michael-aldol-lactonization' reaction afforded 7-hydroxy-6H-benzo[c]chromen-6-ones.
- Ullah, Ehsan,Appel, Bettina,Fischer, Christine,Langer, Peter
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p. 9694 - 9700
(2007/10/03)
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- Analogs of green tea polyphenols as chemotherapeutic and chemopreventive agents
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Novel compounds useful as chemotherapeutic and chemopreventive agents are provided. The compounds are analogs of polyphenol catechins that occur in green tea, such as epigallocatichin-3-gallate (EGCG), and have the structure of formula (I) wherein R1 through R11 are defined herein. Preferred R4 moieties are selected from O, S, NH and CH2, and in exemplary compounds, R4 is O and R5 is a tri-substituted aroyloxy substituent, such as a 3,4,5-substituted benzoyloxy group. Pharmaceutical compositions are provided as well, as are methods of chemotherapy and chemoprevention.
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- Analogs of green tea polyphenols as chemotherapeutic and chemopreventive agents
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Novel compounds useful as chemotherapeutic and chemopreventive agents are provided. The compounds are analogs of polyphenol catechins that occur in green tea, such as epigallocatichin-3-gallate (EGCG), and have the structure of formula (I) wherein R1 through R11 are defined herein. Preferred R4 moieties are selected from O, S, NH and CH2, and in exemplary compounds, R4 is O and R5 is a tri-substituted aroyloxy substituent, such as a 3,4,5-substituted benzoyloxy group. Pharmaceutical compositions are provided as well, as are methods of chemotherapy and chemoprevention.
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- Titanium(IV) chloride-mediated ortho-acylation of phenols and naphthols
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The use of titanium(IV) chloride as a Lewis acid for direct ortho-acylation of phenols and naphthols proves to be a convenient, more general and direct route to various hydroxyaryl ketones. The route is regioselective, leading to ortho C-acylated products in satisfactory to high yields in most cases.
- Bensari, Ahlem,Zaveri, Nurulain T.
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p. 267 - 271
(2007/10/03)
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- Intramolecular Michael-type Addition in the Solid State
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Several substituted 2'-hydroxy-4',6-dimethylchalcones undergo a solid state intramolecular Michael-type addition reaction to yield the corresponding flavanones, at temperatures significantly below the melting points of the reactants or products.Single crystal X-ray diffraction studies of the reactant and product phases have beeen carried out and indicate that these solid state reactions most likely proceed in a non-topochemical fashion.A similar conclusion is deduced from X-ray powder diffraction, differential scanning calorimetry and packing energy calculations.Reaction in the defect regions is probably important because considerable relaxation in the molecular conformation of the chalcone is required in the crystal before intramolecular ring-closure to the flavanone can occur.
- Goud, B. Satish,Panneerselvam, Kaliyamoorthy,Zacharias, David E.,Desiraju, Gautam R.
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p. 325 - 330
(2007/10/02)
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- C-ALKYLATION OF β-DIKETONES WITH BENZYLPYRIDINIUM SALTS. EVIDENCE FOR CHAIN RADICAL MECHANISMS
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1-(p-Substituted benzyl)-2,4,6-triphenylpyridinium cations react with β-diketone anions by mechanisms which depend on the para-substituent.The p-methoxybenzyl derivative undergoes SN1 displacement yielding O- and C-benzylated products.The p-nitrobenzyl compound reacts by a chain radicaloid mechanism and gives high yields of C-p-nitrobenzylated diketones.The parent benzyl compound forms some C- and some O-benzylated products, together with bibenzyl, probably by a radical chain reaction which was suppressed by radical traps.
- Marquet, Jorge,Moreno-Manas, Marcial,Pacheco, Pedro,Prat, Maria,Katritzky, Alan R.,Brycki, Bogumil
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p. 5333 - 5346
(2007/10/02)
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- An Improved Procedure for Mono C-Alkylation of Pentane-2,4-dione with ω-Bromoacid Esters
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Pentane-2,4-dione is alkylated by ethyl bromoacetate or ethyl 6-bromohexanoate in high yield in CH2Cl2 or 5:1 CH3CN-(CH3)2SO solvents, using one equivalent of K2CO3-Cs2CO3 as base.
- Shrout, David P.,Lightner, David A.
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p. 2075 - 2080
(2007/10/02)
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- OXYGEN HETEROCYCLES BY SULPHUR YLIDE ANNULATION. IX. 3,4-DIHYDRO-2-HYDROXYMETHYL-2H,5H-PYRANOBENZOPYRAN-5-ONES FROM 3-(3-OXOALKYL)-4-HYDROXYCOUMARINS AND DIMETHYLSULPHOXONIUM METHYLIDE
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Several 3-(3-oxoalkyl)-4-hydroxycoumarins have been synthesized from the corresponding 4-hydroxycoumarins and they have been reacted with dimethylsulphoxonium methylide.Transfer of one methylene group to the carbonyl function takes place and the regio- and site-selective opening of the so formed epoxide by action of the oxygen in position 4 of the coumarin moiety gives 3,4-dihydro-2-hydroxymethyl-2H,5H-pyranobenzopyran-5-ones in medium to high yields.A full spectral characterization of twenty new products has been made, and a discussion on the different factors controlling the reaction mechanism is also reported.
- Bravo, Pierfrancesco,Resnati, Giuseppe,Ticozzi, Calimero,Arnone, Alberto,Cavicchio, Giancarlo
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p. 501 - 510
(2007/10/02)
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- Alkylation of active methylene compounds with 2-chloromethyl-1,4-dioxane
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The alkylation of some active methylene compounds with 2-chloromethyl-1,4-dioxane was investigated.It was shown that malonic ester gives mono- and dialkylation products, depending on the conditions.The alkylation of acetoacetic ester gives a mixture of C- and O-alkylation products.Acetylacetone is not alkylated under the given conditions but condenses fully, being converted into 2,4-dimethyl-6-hydroxyacetophenone.
- Krasavtsev I. I.,Basalkevich E. D.,Lozinskii M. O.
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p. 1632 - 1634
(2007/10/02)
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- METAL COMPLEXES IN ORGANIC SYNTHESIS-V ALKYLATIONS OF PENTANE-2,4-DIONE WITH ALLYLIC ALCOHOLS UNDER PALLADIUM CATALYSIS
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Pentane-2,4-dione with allylic alcohols or benzyl alcohol with palladium catalysts gives high yields of C-monoalkylated diketones, arising mainly from reaction at the terminal end of the allylic system for alkyl monosubstituted allyl alcohols.The effect of the catalyst on the alcohols has been evaluated; rearrangements and disproportionations have been observed.
- Moreno-Manas, M.,Trius, A.
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p. 3009 - 3016
(2007/10/02)
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