- Photoinduced, Copper-Catalyzed Decarboxylative C-N Coupling to Generate Protected Amines: An Alternative to the Curtius Rearrangement
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The Curtius rearrangement is a classic, powerful method for converting carboxylic acids into protected amines, but its widespread use is impeded by safety issues (the need to handle azides). We have developed an alternative to the Curtius rearrangement that employs a copper catalyst in combination with blue-LED irradiation to achieve the decarboxylative coupling of aliphatic carboxylic acid derivatives (specifically, readily available N-hydroxyphthalimide esters) to afford protected amines under mild conditions. This C-N bond-forming process is compatible with a wide array of functional groups, including an alcohol, aldehyde, epoxide, indole, nitroalkane, and sulfide. Control reactions and mechanistic studies are consistent with the hypothesis that copper species are engaged in both the photochemistry and the key bond-forming step, which occurs through out-of-cage coupling of an alkyl radical.
- Zhao, Wei,Wurz, Ryan P.,Peters, Jonas C.,Fu, Gregory C.
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supporting information
p. 12153 - 12156
(2017/09/12)
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- Visible light-promoted metal-free C-H activation: Diarylketone-catalyzed selective benzylic mono- and difluorination
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We report herein an operationally simple method for the direct conversion of benzylic C-H groups to C-F. We show that visible light can activate diarylketones to abstract a benzylic hydrogen atom selectively. Adding a fluorine radical donor yields the benzylic fluoride and regenerates the catalyst. The selective formation of mono- and difluorination products can be achieved by catalyst control. 9-Fluorenone catalyzes benzylic C-H monofluorination, while xanthone catalyzes benzylic C-H difluorination. The scope and efficiency of this new C-H fluorination method are significantly better than those of the existing methods. This is also the first report of selective C-H gem-difluorination.
- Xia, Ji-Bao,Zhu, Chen,Chen, Chuo
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supporting information
p. 17494 - 17500
(2014/01/06)
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- Photoinduced SET phthalimidation of unactivated double bonds and its application to the synthesis of protected phenethylamines
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Phthalimide, in equilibrium with its conjugate base, adds photochemically to cyclohexene and aryl-substituted alkenes (photophthalimidation). The efficient, predictable regioselective photophthalimidation of styrenes constitutes a synthetically useful process for the preparation of N-phenethyl-phthalimides. A possible mechanism for the photophthalimidation involves the nucleophilic attack of phthalimide anion on the alkene cation-radical generated by single electron transfer to excited phthalimide.
- Suau, Rafael,García-Segura, Rafael,Sánchez-Sánchez, Cristobal,Pérez-Inestrosa, Ezequiel,Pedraza, Ana María
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p. 2913 - 2919
(2007/10/03)
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- Photophthalimidation of unactivated double bonds. Synthesis of protected phenethylamines
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At low hydroxide ion concentrations, the photoaddition of phthalimide to cyclohexene, indene or styrene derivatives takes place. The cation radical obtained in the electron transfer from the alkene to excited phthalimide is trapped by phthalimide anion. At high hydroxide ion concentrations concerted [2+2] cycloaddition occurs that yields benzazepinediones, whatever the ionization potential of the alkene. The most suitable reaction conditions can be inferred from the observed fluorescence of phthalimide anion.
- Suau, Rafael,Garcia-Segura, Rafael,Sanchez, Cristobal,Pedraza, Ana Maria
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p. 2007 - 2010
(2007/10/03)
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- Benzylphthalimides and phenethylphthalimides with thalidomide-like activity on the production of tumor necrosis factor α
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Benzylphthalimide analogs (P1P's) and phenethylphthalimide analogs (P2P's) have been found to exhibit thalidomide-like activity on the production of tumor necrosis factor (TNF)-α by the human leukemia cell line, HL-60, stimulated by 12-O-tetradecanoylphorbol-13-acetate (TPA). Structure-activity relationships are discussed on the basis of the TNF-α production-enhancing activity. Benzylphthalimide (P1P-00) exhibited activity which is weaker than that of thalidomide, but introduction of a methyl group at the ortho-position of the benzyl moiety (P1P-10) resulted an increase to a level comparable with that of thalidomide. Phenethylphthalimide (P2P-00) is more potent than thalidomide, and its fluorinated derivative, 2-phenethyl-4,5,6,7-tetrafluoro- 1H-isoindole-1,3-dione (FP2P-00), exhibited potent activity at very low concentrations.
- Sasaki,Shibata,Hashimoto,Iwasaki
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p. 1228 - 1233
(2007/10/03)
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