- Exploiting photooxygenations mediated by porphyrinoid photocatalysts under continuous flow conditions
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Photooxygenation reactions are a powerful synthetic tool to produce oxidized organic compounds; however, these reactions often exhibit experimental limitations including the production of complex mixtures that hinder desired product isolation and scale-up. Herein, we present a photocatalysed protocol under continuous flow conditions using a simple home built photoreactor and porphyrinoids as photocatalysts. Reaction conditions, long-term experiments, and scope demonstrate a protocol that is cost-effective, safe, reproducible and robust, thus allowing the production of relevant substituted naphthoquinones with interest in natural product synthesis and biological activity.
- De Oliveira, Kleber T.,Miller, L. Zane,McQuade, D. Tyler
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p. 12717 - 12725
(2016/02/12)
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- Rearrangements in the Cerium(IV) and Manganese(III) Oxidations of Substituted Naphthalenes and the NIH Shift Mechanism
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Ceric ammonium sulphate oxidation of 1- and 1,4-disubstituted naphthalenes gives 2- and/or 2,3-disubstituted 1,4-naphthoquinones through migration of substituents (D, Br, Ph).Similar rearrangements are also observed in the manganese(III) oxidation and also in the anodic oxidation of these substrates.The results are consistent with the proposal that these oxidations go through the formation of radical cation followed by reaction with H2O and further oxidation of the radical to the carbocationic intermediate on the way to the corresponding 1,4-naphthoquinone.Oxidation of 1,4-diphenylnaphthalene gives 2,3-diphenyl-1,4-naphthoquinone or 4-hydroxy-2,4-diphenyl-1(4)H-naphthalenone.The results are in accordance with the conclusion that such rearrangements do not require prior formation of arene oxide intermediates, originally proposed for the NIH shift mechanism.
- Bhatt, M. Vivekananda,Periasamy, Mariappan
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p. 3575 - 3586
(2007/10/02)
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