- Electro-mediated PhotoRedox Catalysis for Selective C(sp3)–O Cleavages of Phosphinated Alcohols to Carbanions
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We report a novel example of electro-mediated photoredox catalysis (e-PRC) in the reductive cleavage of C(sp3)?O bonds of phosphinated alcohols to alkyl carbanions. As well as deoxygenations, olefinations are reported which are E-selective and can be made Z-selective in a tandem reduction/photosensitization process where both steps are photoelectrochemically promoted. Spectroscopy, computation, and catalyst structural variations reveal that our new naphthalene monoimide-type catalyst allows for an intimate dispersive precomplexation of its radical anion form with the phosphinate substrate, facilitating a reactivity-determining C(sp3)?O cleavage. Surprisingly and in contrast to previously reported photoexcited radical anion chemistries, our conditions tolerate aryl chlorides/bromides and do not give rise to Birch-type reductions.
- Tian, Xianhai,Karl, Tobias A.,Reiter, Sebastian,Yakubov, Shahboz,de Vivie-Riedle, Regina,K?nig, Burkhard,Barham, Joshua P.
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supporting information
p. 20817 - 20825
(2021/08/18)
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- The vicinal functionalization of olefins: A facile route to the direct synthesis of β-chlorohydrins and β-chloroethers
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An efficient and environmentally benign protocol for the synthesis of vicinal chlorohydroxy and chloromethoxy derivatives in a highly regioselective manner from olefins using NH4Cl as a chlorine source and oxone as an oxidant in aqueous acetone and methanol is demonstrated. This methodology offers an additive and metal chloride free approach and is endowed with simple reaction conditions, high yields a broad substrate scope and good functional group tolerance. Moreover, the aromatic substrates with a terminal double bond exhibited merely Markovnikov selectivity, while the internal alkenes show exclusive regiocontrol and low to moderate diastereoselectivity.
- Swamy, Peraka,Kumar, Macharla Arun,Reddy, Marri Mahender,Naresh, Mameda,Srujana, Kodumuri,Narender, Nama
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p. 26288 - 26294
(2014/07/08)
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- Addition of halide to π-bond directly from aqueous NaX solution: A general strategy for installation of two different functional groups
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Activation of π-bond with organic Lewis acid and cationic surfactant mediated direct transfer of halides to alkyne and alkene are demonstrated to afford α,α-dihaloketones and other valuable synthons with outstanding selectivities.
- Pandit, Palash,Gayen, Krishnanka S.,Khamarui, Saikat,Chatterjee, Nirbhik,Maiti, Dilip K.
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supporting information; experimental part
p. 6933 - 6935
(2011/08/06)
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- THE FORMATION OF CATION-RADICALS BY THE ACTION OF CHLORINE DIOXIDE ON p-SUBSTITUTED STYRENES AND OTHER ALKENES
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The Hammet plot for the reaction of ClO2 with p-substituted styrenes, the solvent effect, and the order of reacivity of several alkenes towards ClO2, indicate that the alkene-ClO2 reaction proceeds via the formation of cation-radicals.
- Choshen (Goldstein), Ehud,Elits, Rudi,Rav-Acha, Chaim
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p. 5989 - 5992
(2007/10/02)
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- Chlorine Dioxide as an Electron-Transfer Oxidant of Olefins
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The kinetics and product studies of oxidation of eight olefins 1-8 by ClO2 in H2O in the pH range 3-7 are described.The reaction is faster as the pH decreases.At pH The order of reactivity is: (E)-stilbene > indene > β-methylstyrene > acenaphthylene > α-methylstyrene > styrene > cyclohexene > allylbenzene.A multi-stage radical-cation mechanism is proposed, in which an initial reversible protonation: is followed by an electron-transfer stage (rate-determining): The cation-radical thus produced, adds rapidly an additional ClO2 to from dioxygenated products.The chlorohydrines most likely arise from HClO additions to the olefinic double bonds, which, in turn, generate from dismutation of 2HClO2 into HClO + H+ + ClO3-.
- Rav-Acha, Chaim,Choshen, Ehud,Sarel, Shalom
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p. 1728 - 1733
(2007/10/02)
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