- Tridemethylisovelleral, a potent cytotoxic agent
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The synthesis and in vitro cytotoxicity toward various tumor cell lines of (±)-tridemethylisovelleral, an analogue of the bioactive fungal sesquiterpene (+)-isovelleral retaining the bicyclo[4,1,0]hept-2-en-1,2- dicarbaldehyde system but lacking the three methyl groups, is reported. The cytotoxicity of tridemethylisovelleral toward several tumor cell lines was found to be comparable with those of established antitumor drugs, and significantly higher than that of isovelleral.
- Aujard, Isabelle,Roeme, Daniel,Arzel, Erwan,Johansson, Martin,De Vos, Dick,Sterner, Olov
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- Dehydrogenation of polycyclic ketones using trichloromethyl cation in superacid
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In HF/SbF3/CCl4 bicyclic cyclohexanones are dehydrogenated to enones and dienones, superelectrophilic trichloromethyl cation CCl3+ reacting as a strong hydride acceptor. Dehydrogenation is also observed with steroidal enones.
- Martin, Agnes,Jouannetaud, Marie-Paule,Jacquesy, Jean-Claude
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- Use of the bifunctional reagent (Z)-4-iodo-1-(tributylstannyl)but-1-ene: A new cyclohexenone annulation method
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A new cyclohexenone annulation method, based on the use of the bifunctional reagent (Z)-4-iodo-1-(tributylstannyl)but-l-ene (6) and exemplified by conversion of the substrate 8 into the annulated products 13 and 18 and of the starting materials 19-23 into the products 34-38, respectively, is described.
- Piers, Edward,Boulet, Serge L.
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- Cascade Radical Cyclization-Fragmentation-Transannular-Ring Expansion Reactions Involving Oximes. A New Approach to the Synthesis of Angular Triquinanes
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Treatment of the acetylene-substituted cyclobutanone oxime ether (13) with (Me3Si)3SiH leads, in one pot, to the 5,6-bicyclic enone oxime (14) in 70percent yield.It is suggested that the formation of (14) from (13) proceeds by way of a novel double ring e
- Hollingworth, Gregory J.,Pattenden, Gerald,Schulz, Darren J.
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p. 381 - 400
(2007/10/02)
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- A new method for the preparation of Michael adducts and cyclic enones using lithium chloride-hexamethylphosphoramide system
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A new procedure using lithium chloride in hexamethylphosphoramide was found to be useful for the synthesis of Michael-type adducts and cyclic enones. Selectivity for the two products could be controlled by altering the reaction temperature employed. The urea-type solvents were also examined instead of hexamethylphosphoramide.
- Ozaki,Kubo,Okamura,Kim
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p. 734 - 737
(2007/10/02)
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- A Method for the Cyclic Enone Synthesis Using Lithium Chloride-Hexamethylphosphoramide System
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Cyclic enones were obtained from the reactions of β-keto esters with acyclic α,β-unsaturated ketones by using lithium chloride in hexamethylphosphoramide.The products were brought via the Michael addition, decarboxylation, and the aldol condensation.
- Ozaki, Yutaka,Kubo, Ayako,Kim, Sang-Won
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p. 993 - 994
(2007/10/02)
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- Cascade radical reactions in synthesis. A new radical mediated double ring expansion-cyclisation process oxime ethers
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Treatment of the acetylene substituted cyclobutanone oxime ether (1) with (Me3Si)3SiH leads, in one pot, to the bicycle (2, 70%) by way of a novel double ring expansion-cyclisation process involving aminyl radical intermediates.
- Pattenden,Schultz
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p. 6787 - 6790
(2007/10/02)
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- A New Annulation Reagent, 2-Oxo-3-alkenylphosphonates. Reactions with Carbonyl-Stabilized Carboanions or Silyl Enol Ethers Leading to Cyclohexanones
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The reactions of 2-oxo-3-alkenylphosphonates with carbonyl-stabilized carbanions directly lead to 2-cyclohexen-1-ones through a sequence of Michael reaction and intramolecular Horner-Emmons olefination.On the other hand, the Lewis acid-mediated reactions with silyl enol ethers produce 1,5-diketones as Michael adducts, which then undergo cyclization on treatment with sodium hydride or triethylamine/zinc (II) bromide to afford 2-cyclohexen-1-ones or 2-phosphinyl-2-cyclohexen-1-ones, respectively.
- Wada, Eiji,Funakoshi, Junji,Kanemasa, Shuji
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p. 2456 - 2464
(2007/10/02)
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- Organotin Triflate as Practical Catalyst for Michael Addition of Enol Silyl Ethers
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Dibutyltin bis(triflate) is a mild Lewis acid which catalyzes clean Michael addition of enol silyl ethers.The new catalyst allows to employ various labile acceptors such as methyl vinyl ketone and 2-cyclopentenone which do not undergo smooth reaction with
- Sato, Tsuneo,Wakahara, Yoshiyuki,Otera, Junzo,Nozaki, Hitosi
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p. 9773 - 9782
(2007/10/02)
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- Organotin triflates as functional Lewis acids. A new entry to simple and efficient Robinson annulation
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An efficient Robinson annulation has been established through the Michael addition of enol silyl ethers to α-enones catalyzed by dibutyltinbis(triflate) followed by the MeONa-mediated intramolecular aldol condensation of the adducts.
- Sato, Tsuneo,Wakahara, Yoshiyuki,Otera, Junzo,Nozaki, Hitosi
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p. 1581 - 1584
(2007/10/02)
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- NOVEL RING EXPANSION OF CYCLOPENTANONES TO SEVEN MEMBERED RINGS
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By treatment with BF3/ethyleneglycol, cyclopentanones with the carbonyl function at the C3-position of α-side chain undergo the ring cleavage to build up the seven membered rings, and this novel ring expansion was applied to the synthesis of bulnesol.
- Tanaka, Masakazu,Suemune, Hiroshi,Sakai, Kiyoshi
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p. 1733 - 1736
(2007/10/02)
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- Observations sur l'hydrolyse d'acetals dihydropyranniques
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The hydrolysis of of dihydropyranyl acetals by sulfuric acid leads to cyclenones, but by the use of pyridinium p-tolenesulfonate, δ-ketoaldehydes may be isolated.These compounds do not undergo aldol condensation under these conditions.
- Thuy, Vu Moc,Maitte, Pierre
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p. 497 - 499
(2007/10/02)
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- A CONVENIENT PROCEDURE FOR CARBOXYLATION-ROBINSON ANNULATIONS OF KETONES USING TRIETHYLAMINE BASE IN THE PRESENCE OF MAGNESIUM CHLORIDE
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Carboxylation of ketones with carbon dioxide in the presence of magnesium chloride and triethylamine followed by reaction with methyl vinyl ketone gives satisfactory yields of Michael and Robinson annulation products.
- Olsen, Richard S.,Fataftah, Zakaria A.,Rathke, Michael W.
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p. 1133 - 1140
(2007/10/02)
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- Cumulated Ylides, XVII. Synthesis of Cyclic Compounds from Triphenylphosphorane and Oxocarboxylic Acids - A Novel Method for Anellation
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By entropically supported intramolecular Wittig reaction from α-keto carboxylic acids 23 with triphenylphosphorane (1) N-phenylmaleinisoimides 26 and -imides 29 are formed.The compounds 26 can be rearranged into 29 with a catalytic amount of sodium azide. - From γ-keto carboxylic acids 30 3-substituted 2-cyclopenten-1-ones 37 can be derived via the 3,6-dioxo-2-(triphenylphosphoranylidene)alkananilides 33.Analogously, 3-substituted 2-cyclohexen-1-ones 49 are formed from δ-keto carboxylic acids 46. o-Acylbenzoic acids 38, in the case R = H, are converted with 1 into the benzazepinedione derivative 44, and in the case R unlike H into 3-substituted 1-oxo-1H-indene-2-carboxanilides 45. - Starting from oxo carboxylic acids, possessing the carbonyl function in a ring, five- and six-membered rings can be anellated in a simple way.
- Bestmann, Hans Juergen,Schade, Gerold,Luetke, Harry,Moenius, Thomas
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p. 2640 - 2658
(2007/10/02)
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- NOUVELLE METHODE D'ANNELATION PAR L' INTERMEDIAIRE DE DICETONES-1,5
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A new method for six-membered ring annelation is described which involved reaction of hemiacetal vinylogs 1 with silyl enol ethers 2 in the presence of a Lewis acid.
- Duhamel, Pierre,Poirier, Jean-Marie,Tavel, Gilbert
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- The Rearrangements of the Nitrones of Simple Cyclic Conjugated Ketones
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The ring expansions of N-methyl nitrones formed from cyclic conjugated ketones have been investigated.Low yields of cyclic amides were obtained.In general, the best conditions for the rearrangement involved using p-toluenesulfonyl chloride and polyphosphoric acid in tetrahydrofuran.The parent ketone and, in some cases, an N-aryl sulfonamide were also obtained; mechanisms for their formation are discussed.
- Prager, Rolf H.,Raner, Kevin D.,Ward, A. David
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p. 381 - 387
(2007/10/02)
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- LATENT ACETONYLATION OF α,β-ENONES WITH ALLYLTRIMETHYLSILANE OR 2-METHYL-2-PROPENYLTRIMETHYLSILANE: SYNTHESIS OF 1,5-DIKETONES AND ANNELATION TO FUSED CYCLOHEXENONES
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Acetonylation of α,β-enones can be achieved by either with (2-methyl-2-propenyl)trimethylsilane or with allyltrimethylsilane followed by oxidative cleavage of the double bond or by the Wacker reaction, respectively.Annelation of the 1,5-diketones is also
- Hosomi, Akira,Kobayashi, Hiroshi,Sakurai, Hideki
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p. 955 - 958
(2007/10/02)
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- Bicycloalkanes
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Bicycloalkane derivatives of the formula STR1 WHEREIN N IS 1 OR 2, R1 is lower alkyl, X is free or ketalized carbonyl or a free, esterified, or etherified hydroxymethylene, and Y is --S--R2, --SOm --R2, or STR2
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