- Deconjugative α-Alkylation of Cyclohexenecarboxaldehydes: An Access to Diverse Terpenoids
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A general and efficient method for the deconjugative α-alkylation of α,β-unsaturated aldehydes promoted by a synergistic effect between tBuOK and NaH, which considerably increases the reaction rate under mild conditions, is reported. The β,γ-unsaturated aldehyde, resulting from the α-alkylation, is transformed in high yield into the corresponding allyl acetate via a lead(IV) acetate-mediated oxidative fragmentation. This strategy could be used for the construction of the carbon skeleton of a wide variety of alkyl or arylterpenoids.
- Chahboun, Rachid,Botubol-Ares, José Manuel,Durán-Pe?a, María Jesús,Jiménez, Fermín,Alvarez-Manzaneda, Ramón,Alvarez-Manzaneda, Enrique
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p. 8742 - 8754
(2021/07/19)
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- Copper(I)-catalyzed intramolecular O-arylation for the synthesis of 2,3,4,9-tetrahydro-1 H -xanthen-1-ones with low loads of CuCl
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As little as 0.5 mol % CuCl is sufficient to catalyze the intramolecular O-arylation of easily accessible 2-(2-bromobenzyl)cyclohexane-1,3-diones to provide the corresponding 2,3,4,9-tetrahydro-1H-xanthen-1-ones with yields ranging from 83% to 99%.
- Sudheendran, Kavitha,Malakar, Chandi C.,Conrad, Juergen,Beifuss, Uwe
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p. 10194 - 10210
(2013/01/15)
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- Intramolecular direct dehydrohalide coupling promoted by KOtBu: Total synthesis of amaryllidaceae alkaloids anhydrolycorinone and oxoassoanine
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A transition-metal-free intramolecular dehydrohalide coupling via intramolecular homolytic aromatic substitution (HAS) with aryl radicals has been developed in the presence of potassium tert-butoxide and an organic molecule as the catalyst. The methodology has been applied to a concise synthesis of Amaryllidaceae alkaloids viz. oxoassoanine (1b), anhydrolycorinone (1d), and other related structures. Interestingly, the method also works only in the presence of potassium tert-butoxide.
- De, Subhadip,Ghosh, Santanu,Bhunia, Subhajit,Sheikh, Javeed Ahmad,Bisai, Alakesh
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supporting information
p. 4466 - 4469
(2012/10/29)
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- Cu(I)-Catalyzed domino reactions: Efficient and selective synthesis of 4h-chromenes and naphthalenes
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Depending on the ratio of the substrates and the reaction conditions, the Cu(I)-catalyzed domino reaction between bromobenzyl bromides and β-ketoesters exclusively yields either 4H-chromenes or naphthalenes.
- Malakar, Chandi C.,Schmidt, Dietmar,Conrad, Juergen,Beifuss, Uwe
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supporting information; experimental part
p. 1972 - 1975
(2011/06/19)
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- Synthesis of N-alkoxyindol-2-ones by copper-catalyzed intramolecular N-arylation of hydroxamates
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The first example of copper-catalyzed intramolecular N-arylation of hydroxamic acid derivatives is presented. Based on this transformation a new method for the synthesis of N-alkoxyindol-2-ones from 2-(2-bromoaryl) acetylhydroxamates has been developed. T
- Kukosha, Tatyana,Trufilkina, Nadezhda,Katkevics, Martins
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supporting information; scheme or table
p. 2525 - 2528
(2011/11/13)
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- NOVEL THIOPHENE AMIDINES, COMPOSITIONS THEREOF, AND METHODS OF TREATING COMPLEMENT-MEDIATED DISEASES AND CONDITIONS
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Disclosed is a method for treating the symptoms of an acute or chronic disorder mediated by the classical pathway of the complement cascade, comprising administering to a mammal in need of such treatment a therapeutically effective amount of a compound of Formula (I) or a solvate, hydrate or pharmaceutically acceptable salt thereof; wherein R1, R2, R3, R4 and R7 are defined in the specification, Z is SO or SO2, and Ar is an aromatic or heteroaromatic group as defined herein.
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Page 418-419
(2010/02/05)
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- Diversity-oriented synthesis of biaryl-containing medium rings using a one bead/one stock solution platform
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Diversity-oriented synthesis of structurally complex and diverse small molecules can be used as the first step in a process to explore cellular and organismal pathways. The success of this process is likely going to be dependent on advances in the synthesis of small molecules having natural product-like structures in an efficient and stereoselective manner. The development, scope, and mechanism of the oxidation of organocuprates was investigated and exploited in the atropdiastereoselective synthesis of biaryl-containing medium rings (9-, 10-, and 11-membered rings). The methodology was performed on high-capacity, large polystyrene beads by metalating aryl bromides with-iPrBu2MgLi, followed by transmetalating with CuCN·2LiBr and then oxidizing with 1,3-dinitrobenzene, and was used in a diversity-oriented synthesis of biaryl-containing medium rings (library total theoretical maximum 1412 members). The high capacity beads were arrayed into 384-well plates and, using a process optimized during the development of a one bead/one stock solution technology platform, converted into arrays of stock solutions, with each stock solution containing largely one compound. These stock solutions were used in numerous phenotypic and proteinbinding assays. The process described outlines a pathway that we feel will contribute to a comprehensive and systematic chemical approach to exploring biology (chemical genetics).
- Spring, David R.,Krishnan, Shyam,Blackwell, Helen E.,Schreiber, Stuart L.
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p. 1354 - 1363
(2007/10/03)
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- The first total synthesis of toddaquinoline, an alkaloid from Toddalia asiatica
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The paper describes the first total synthesis of toddaquinoline, an alkaloid from the root bark of Formosan Toddalia asiatica. The key step is cobalt(I) mediated radial cyclisation to a pyridine. Cobalt appears to play a dual role in the reaction, firstly initialising homolysis of the carbon to halogen bond then acting as a Lewis acid to promote cyclisation to C-6. Other approaches examined are also outlined. These include a photocyclisation of an azastilbene; a cyclisation induced by halogen to metal exchange and a tin mediated radical cyclisation.
- Harrowven, David C.,Nunn, Michael I.T.,Blumire, Nigel J.,Fenwick, David R.
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p. 4447 - 4454
(2007/10/03)
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- Intramolecular radical additions to quinolines
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This paper is concerned with intramolecular radical additions to quinolines. Radical additions to C-2, C-3 and C-4 of a quinoline have all been shown to proceed under neutral conditions. In each case formation of heteroaromatic products, rather than dihydroquinolines, was observed (implicating the so called oxidative tin hydride pathway).
- Harrowven, David C.,Sutton, Benjamin J.,Coulton, Steven
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p. 2907 - 2910
(2007/10/03)
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- A Convenient Strategy for the Synthesis of 4,5-Bis(o-haloaryl)isoxazoles
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A series of new 1,2-bis(o-haloaryl)ethanones is efficiently prepared and applied to the synthesis of 4,5-bis(o-haloaryl)isoxazoles. Isolation of intermediate hydroxyisoxazolines, which are structurally examined, provides a definitive proof for a heterocyclization mechanism based on an amine exchange process. The isolation and X-ray crystallographic studies of significant side products such as benzamides and triarylpropionitriles are also described.
- Olivera, Roberto,SanMartin, Raul,Dominguez, Esther,Solans, Xabier,Urtiaga, Miren Karmele,Arriortua, Maria Isabel
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p. 6398 - 6411
(2007/10/03)
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- A total synthesis of toddaquinoline exposes a dual role for cobalt in radical additions to pyridines
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This paper describes the first total synthesis of toddaquinoline, an alkaloid from the root bark of Formosan Toddalia asiatica. Importantly, the synthesis has exposed a dichotomy in radical reactions mediated by tin and cobalt(I) that involve additions to pyridines. Our observations suggest that cobalt plays a dual role in such reactions: Firstly initiating homolysis of the carbon to halogen bond, then acting as a Lewis acid to promote radical additions to the carbon centre adjacent to nitrogen. (C) 2000 Elsevier Science Ltd.
- Harrowven,Nunn,Blumire,Fenwick
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p. 6681 - 6683
(2007/10/03)
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- The intramolecular addition of an aryl radical to a pyridine provides a short entry to toddaquinoline
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The paper describes a synthetic approach to toddaquinoline, an unusual alkaloid from the root bark of Formosan Toddalia asiatica. Key steps are a cis-selective Wittig coupling and a trialkyltin mediated, intramolecular cyclisation of an aryl radical to C-
- Harrowven, David C.,Nunn, Michael I.T.
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p. 5875 - 5876
(2007/10/03)
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- A new route to γ-arylidenebutyrolactones via a tandem carbopalladation-heterocyclisation sequence: A formal synthesis of U-68,215
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Benzo-annulated enol lactones are obtained in good yields from pentynoic acids 3- or 5-substituted with an iodo-aryl moiety by palladium-catalyzed cyclization of their potassium carboxylates. Using this approach, an efficient new route to U-68,215 is described.
- Cavicchioli, Marcello,Decortiat, Sylvie,Bouyssi, Didier,Gore, Jacques,Balme, Genevieve
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p. 11463 - 11478
(2007/10/03)
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- Tandem Pummerer-Diels-Alder reaction sequence. A novel cascade process for the preparation of 1-arylnaphthalene lignans
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The α-thiocarbocation generated from the Pummerer reaction of an o-benzoyl-substituted sulfoxide is intercepted by the adjacent keto group to produce an α-thio isobenzofuran as a transient intermediate which undergoes a subsequent Diels-Alder cycloadditio
- Padwa, Albert,Cochran, John E.,Kappe, C. Oliver
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p. 3706 - 3714
(2007/10/03)
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- Methylendioxyphenathrene and stilben derivatives, process for the preparation thereof, pharmaceutical compositions using these, and therapeutic applications
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The present invention provides compounds of the general formula: STR1 wherein R1 is a hydrogen atom or a methoxy or ethoxy radical and R2 and R3 are hydrogen atoms or R2 and R3 together represent an aromatic carbon-carbon bond and R1 is a hydrogen atom, a hydroxyl group or an ethoxy radical; and the pharmaceutically acceptable salts thereof. The present invention also provides processes for the preparation of these compounds and pharmaceutical compositions containing them, as well as their use in therapy.
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- Sythesis of 2,2'-Diacyl-1,1'-biaryls. Regiocontrolled Protection of Ketones in Unsymmetrically Substituted 9,10-Phenanthrenequinones
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A regiocontrolled monoketalization of unsymmetrically substituted phenanthrenequinones by use of 2,2-dimethyl-1,3-propanediol as the ketalizing reagent has been effected with the help of bromo substitution in one of the aromatic rings at the C-1 or C-8 po
- Mervic, Miljenko,Ghera, Eugene
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p. 4720 - 4725
(2007/10/02)
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