- Practical Chemoselective Acylation: Organocatalytic Chemodivergent Esterification and Amidation of Amino Alcohols with N-Carbonylimidazoles
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Chemoselective transformations are a cornerstone of efficient organic synthesis; however, achieving this goal for even simple transformations, such as acylation reactions, is often a challenge. We report that N-carbonylimidazoles enable catalytic chemodivergent aniline or alcohol acylation in the presence of pyridinium ions or 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), respectively. Both acylation reactions display high and broad chemoselectivity for the target group. Unprecedented levels of chemoselectivity were observed in the DBU-catalyzed esterification: A single esterification product was obtained from a molecule containing primary aniline, alcohol, phenol, secondary amide, and N?H indole groups. These acylation reactions are highly practical as they involve only readily available, inexpensive, and relatively safe reagents; can be performed on a multigram scale; and can be used on carboxylic acids directly by in situ formation of the acylimidazole electrophile.
- Brown, Hailee,Heller, Stephen T.,Light, Christina,Medlin, Abigail,Nelson, Hope,Richard, William
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supporting information
p. 22818 - 22825
(2021/09/13)
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- Facile one-pot synthetic access to libraries of diversely substituted 3-aryl (Alkyl)-coumarins using ionic liquid (IL) or conventional base/solvent, and an IL-mediated approach to novel coumarin-bearing diaryl-ethynes
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The in-situ formed carbonylimidazole derivatives of Ar(alkyl)-CH2COOH react at r.t. with substituted salicylaldehydes in [BMIM][PF6] or [BMIM][BF4] as solvent, and [PAIM][NTf2] as basic-IL, to produce libraries of 3-aryl(alkyl)coumarins. Whereas these reactions can also be performed with similar efficiency in THF by employing DBU, the IL approach offers easier work-up and recycling of the IL solvent. An IL-mediated approach to the synthesis of novel coumarin-bearing diaryl-ethynes by the Sonogshira reaction is also reported, and the potential for recycling/reuse of the IL solvent is shown.
- Kalkhambkar, Rajesh G.,Laali, Kenneth K.,Malunavar, Shruti S.,Prabhala, Pavankumar,Savanur, Hemantkumar M.,Sutar, Suraj M.
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supporting information
(2020/04/08)
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- Efficient CDI/CH3SO3H-catalyzed, microwave-assisted synthesis of 2-substituted benzothiazoles
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CDI combined with CH3SO3H was found to be highly effective for the cyclization of 2-aminothiophenol derivatives with carboxylic acids under MW condition. Fourteen benzothiazole derivatives were synthesized in good yield and their structures were characterized by1H-NMR,13C-NMR, IR and mass spectrometry. This simple, rapid synthetic method is believed to provide a useful process for the synthesis of 2-substituted benzothiazole compounds.
- Li, Yao-Wei,Zhang, Pei-Ming,Li, Rui,Bai, Yan,Yu, Yu,Gan, Zong-Jie
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supporting information
p. 34 - 39
(2019/05/04)
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- PROCESS FOR THE PREPARATION OF ENANTIOMERICALLY ENRICHED DIHYDROBENZOFURANS AND INTERMEDIATE COMPOUNDS OBTAINED IN THE PROCESS
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It is described an industrially viable and advantageous process for the preparation of (N- (((1R,2R)-2-(2,3-dihydrobenzofuran-4-yl)cyclopropyl)methyl)propionamide, compound having the formula depicted below and generally known as Tasimelteon, or of intermediates useful in the synthesis thereof: The invention also relates to salts obtained as intermediates of the process.
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Page/Page column 24
(2018/09/12)
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- N-Heterocyclic carbene-catalyzed enantioselective annulations: A dual activation strategy for a formal [4+2] addition for dihydrocoumarins
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A highly efficient asymmetric formal [4+2] annulation for the synthesis of dihydrocoumarins has been developed via an in situ activated NHC catalysis. Both electrophilic and nucleophilic species are generated in situ simultaneously whereby acyl imidazoles facilitated rapid formation of an NHC-enolate intermediate to afford the [4+2] dihydrocoumarin adducts.
- Lee, Anna,Scheidt, Karl A.
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supporting information
p. 3407 - 3410
(2015/03/18)
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- Electroreductive acylation of aromatic imines with acylimidazoles
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The intermolecular reductive coupling of aromatic imines with acylimidazoles was effected by electroreduction in the presence of chlorotrimethylsilane and gave α-amino-α-aryl ketones. This method was also effective for the synthesis of α-amino-α-aryl esters using methoxycarbonylimidazole as an electrophile.
- Kise, Naoki,Morimoto, Shinji
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p. 1765 - 1771
(2008/09/18)
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- Electroreductive acylation of aromatic ketones with acylimidazoles
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The intermolecular reductive coupling of aromatic ketones with acylimidazoles was effected by electroreduction in the presence of chlorotrimethylsilane and gave α-trimethylsiloxy ketones and esters. The best result was obtained using Bu4NPF6 as a supporting electrolyte and a Pb cathode in THF. The α-trimethylsiloxy-containing products were transformed to the corresponding α-hydroxy ketones and esters by treatment with TBAF in THF. This method was also effective for the intramolecular reductive coupling of δ- and ε-keto acylimidazoles.
- Kise, Naoki,Agui, Syun,Morimoto, Shinji,Ueda, Nasuo
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p. 9407 - 9410
(2007/10/03)
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- The selective reaction of primary amines with carbonyl imidazole containing compounds: Selective amide and carbamate synthesis
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matrix presented A new highly selective synthesis of amides and carbamates is described. In both cases the syntheses involve the formation of carbonyl imidazole intermediates which subsequently undergo previously unreported selective reactions with primary amines. Acid imidazolides with sufficient chain length will exclusively react with primary amines even in the presence of secondary and tertiary functionality. The imidazole carboxylic esters of secondary or tertiary alcohols also react selectively with primary amines, forming controlled carbamate structures.
- Rannard, Steve P.,Davis, Nicola J.
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p. 2117 - 2120
(2007/10/03)
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- New Tetracyclic Derivatives of Imidazobenzodiazepines and of Imidazothienodiazepines
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The synthesis of new tetracyclic 1,4-diazepine derivatives is described.In these compounds, an additional five-membered heterocycle is fused on the known tricyclic ring systems imidazobenzodiazepine and imidazothienodiazepine.Many of these new compounds display a very high affinity to the benzodiazepine receptor in mammals.
- Gerecke, Max,Kyburz, Emilio,Borer, Rene,Gassner, Walter
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p. 693 - 722
(2007/10/02)
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- A New Route to 1,3-Diacyl-2,3-dihydro-1H-imidazoles
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Preparative amounts of the title compounds can be prepared in high purity by hydrogenation of the corresponding 1,3-diacylimidazolium salts with sodium borohydride.Structures are confirmed by spectroscopic methods and in two cases by X-ray structure determination.
- Plath, Martin Wolfgang,Scharf, Hans-Dieter,Raabe, Gerhard,Krueger, Carl
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p. 951 - 955
(2007/10/02)
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