- Photocatalytic decarboxylative alkenylation of α-amino and α-hydroxy acid-derived redox active esters by NaI/PPh3 catalysis
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Herein, we report the photocatalytic decarboxylative alkenylation reactions of N-(acyloxy)phthalimide derived from α-amino and α-hydroxy acids with 1,1-diarylethene, and with cinnamic acid derivatives through double decarboxylation, using sodium iodide and triphenylphosphine as redox catalysts. The reaction proceeds under mild irradiation conditions with visible blue light (440 nm or 456 nm) in an acetone solvent without recourse to transition-metal or organic dye based photoredox catalysts. The reaction proceeds via photoactivation of a transiently self-assembled chromophore from N-(acyloxy)phthalimide and NaI/PPh3. Solvation plays a crucial role in the reactivity.
- Fu, Ming-Chen,Fu, Yao,Shang, Rui,Wang, Ya-Ting,Zhao, Bin
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supporting information
p. 2495 - 2498
(2020/03/06)
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- Direct conversion of aldehydes and ketones to allylic halides by a NbX 5-[3,3] rearrangement
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Sequential addition of vinylmagnesium bromide and NbCl5, or NbBr5, to a series of aldehydes and ketones directly provides homologated, allylic halides. Transposition of the intermediate vinyl alkoxide is envisaged through a metalo-halo-[3,3] rearrangement with concomitant delivery of the halogen to the terminal carbon. The [3,3] rearrangement is equally effective for the conversion of a propargyllic alcohol to the corresponding allenyl bromide. Georg Thieme Verlag Stuttgart.
- Fleming, Fraser F.,Ravikumar,Yao, Lihua
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experimental part
p. 1077 - 1080
(2009/09/29)
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- Allylic and allenic halide synthesis via NbCl5- and NbBr 5-mediated alkoxide rearrangements
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(Chemical Equation Presented) Addition of NbCl5 or NbBr 5 to a series of magnesium, lithium, or potassium allylic or propargylic alkoxides directly provides allylic or allenic halides. Halogenation formally occurs through a metallahalo-[3,3] rearrangement, although concerted, ionic, and direct displacement mechanisms appear to operate competitively. Transposition of the olefin is equally effective for allylic alkoxides prepared by nucleophilic addition, deprotonation, or reduction. Experimentally, the niobium pentahalide halogenations are rapid, afford essentially pure (E)-allylic or -allenic halides after extraction, and are applicable to a range of aliphatic and aromatic alcohols, aldehydes, and ketones. 2009 American Chemical Society.
- Ravikumar,Yao, Lihua,Fleming, Fraser F.
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supporting information; experimental part
p. 7294 - 7299
(2010/01/16)
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