- Electroreductive coupling of aromatic ketones, aldehydes, and aldimines with α,β-unsaturated esters: Synthesis of 5-aryl substituted γ-butyrolactones and lactams
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The electroreductive intermolecular coupling of aromatic ketones and aldehydes with α,β-unsaturated esters in the presence of TMSCl gave the adducts as γ-trimethylsiloxy esters. The detrimethylsilylation of the adducts with TBAF afforded 5-aryl substituted γ-butyrolactones. The electroreductive coupling of N-(4-methoxyphenyl)-1-arylmethaneimines with methyl acrylate in the presence of TMSCl gave the adducts as methyl 4-aryl-4-((4-methoxyphenyl)amino)butanoates. The adducts were transformed to 5-aryl-γ-butyrolactams by cyclization with NaH and subsequent oxidation with CAN. (±)-Norcotinine was prepared from nicotinaldehyde by this method. The electroreductive coupling of aromatic ketones and aldimines with acrylonitrile in the presence of TMSCl gave 4-aryl-4-(trimethylsiloxy)butanenitriles and 4-aryl-4-((4-methoxyphenyl)amino)butanenitriles, respectively.
- Kise, Naoki,Hamada, Yusuke,Sakurai, Toshihiko
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p. 1143 - 1156
(2017/02/18)
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- MnO2-promoted carboesterification of alkenes with anhydrides: A facile approach to γ-lactones
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An efficient carboesterification of alkenes with anhydrides promoted by MnO2 has been developed to afford functionalized γ-lactones in good to excellent yields. This method shows a broad substrate scope and provides a valuable and convenient synthetic tool for constructing γ-lactones.
- Wu, Lihuan,Zhang, Zhenming,Liao, Jianhua,Li, Jianxiao,Wu, Wanqing,Jiang, Huanfeng
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supporting information
p. 2628 - 2631
(2016/02/18)
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- Diastereoselective synthesis of highly substituted five-membered-ring oxygen heterocycles by zirconocene-mediated C - C coupling reactions
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As homoenolate equivalents, zirconocene-1-aza-1,3-diene complexes were used for the first time in stereoselective synthesis. By insertion of an unsymmetrical ketone in the Zr-C σ bond, sterically demanding trisubstituted dihydro- and tetrahydrofuran derivatives were prepared in good overall yields and with high diastereoselectivities (see below).
- Enders, Dieter,Kroll, Manfred,Raabe, Gerhard,Runsink, Jan
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p. 1673 - 1675
(2007/10/03)
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- Benzotriazole- and 1,2,4-triazole-stabilized allylic anions: Applications in syntheses of functionalized α,β-unsaturated ketones, γ-lactones, γ-lactams, and β-substituted esters
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Deprotonated 1-(benzotriazol-1-yl)-1-ethoxy-2-hexene (7) reacted with alkyl halides, aldehydes, ketones, imines, and α,β-unsaturated esters to give exclusively the α-alkylated products 8a-c, 10a,b, 12, 14, 16, and 18a,b, respectively. Without isolation, these products were hydrolyzed under mild conditions to generate the corresponding simple or functionalized α,β-unsaturated ketenes 9a-c, 11a,b, 13, 15, 17, and 19a,b. Similar reactions with the phenyl-substituted analog 3-(benzotriazol-1-yl)-3-ethoxy-1-phenyl-1-propene (21) also gave the analogous α-products, but they were accompanied by small amounts of the γ-products in most cases. By contrast, deprotonation of the corresponding triazole derivative 29 with butyllithium followed by reactions with alkyl halides, aldehydes, ketones, or imines yielded exclusively γ-alkylated adducts 32, 34, 36, 38, 40, and 42. Intermediates 32, 34, 36, 38, 40, and 42 were readily converted into β-substituted esters 33a-c, γ-lactones 35a,b, 39, 41, and 43, and γ-lactams 37a-c on hydrolysis.
- Katritzky,Feng,Lang
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p. 706 - 714
(2007/10/03)
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- Direct generation of lithium homoenolates from 3-aryl α,β-unsaturated ketones or esters by an arene-catalysed lithiation: Synthesis of substituted tetrahydrofurans and γ-butyrolactones
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The reaction of α,β-unsaturated ketones 1 with an excess of lithium powder, a catalytic amount of naphthalene (4%) and different carbonyl compounds in the presence of boron trifluoride in THF at -78-0°C yields, after treatment with silyl nucleophile and final hydrolysis, the expected substituted tetrahydrofurans 5. Similar methodology applied to β-aryl acrylic esters 6, but without using boron trifluoride or silyl reagents yields the corresponding lactones 7.
- Alonso, Emma,Ramon, Diego J.,Yus, Miguel
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p. 2641 - 2652
(2007/10/03)
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- Oxidative Ring-Opening Reaction of Cyclopropanone Acetals with Carbonyl Compounds via Photoinduced Electron Transfer. Generation of a β-Carbonyl Radical Species and Its Application to the Synthesis of γ-Hydroxy Ester Derivatives
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Photoinduced electron transfer (PET) reactions of 2-substituted or 2,2-disubstituted cyclopropanone methyl trialkylsilyl acetals 1a-e,g and 1-siloxy-2-oxabicyclohexane (1f) with carbonyl compounds 2 (benzophenone (2a), acetophenone (2b), 2-acetonaphthone (2c), 2-acetylpyridine (2d), 4-acetylbenzonitrile (2e), 2,3-butanedione (2f), and benzoyl cyanide (2g)) were examined in the presence of Mg(ClO4)2.Carbon-carbon bond coupling products (γ-hydroxy esters 3 or their derivative butyrolactones 4) between 1 and 2 were formed in good yields.A mechanism is proposed for the product formation which is initiated by the single electron transfer (SET) from 1 to the excited state of 2.The set generates a transient pair of ion radicals, i.e. a ring-opened sec- or tert-β-carbonyl radical from 1 and a ketyl radical ion from 2 stabilized by the Mg salt.This realizes a novel type of carbon-carbon bond formation at the sterically crowded β-position of propanoates.
- Abe, Manabu,Oku, Akira
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p. 3065 - 3073
(2007/10/02)
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- The Reaction of Olefins with Malonic Acid in the Presence of Manganese(III) Acetate
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The reaction of 1,1-diphenylethene with malonic acid in the presence of manganese(III) acetate gave 3,3,8,8-tetraphenyl-2,7-dioxaspirononane-1,6-dione and 4,4-diphenyl-2-(2,2-diphenylethenyl)-4-butanolide.Similar reactions with 1,1-bis(4-methoxyphenyl)ethene, methylenecyclohexane, 2-phenylpropene, 1-octene, and cyclohexene yielded the corresponding 2,7-dioxaspirononane-1,6-diones.
- Ito, Nobuyuki,Nishino, Hiroshi,Kurosawa, Kazu
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p. 3527 - 3528
(2007/10/02)
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