- Profiling the oxidative activation of DMSO-F6 by pulse radiolysis and translational potential for radical C-H trifluoromethylation
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The oxidative activation of the perfluorinated analogue of dimethyl sulfoxide, DMSO-F6, by hydroxyl radicals efficiently produces trifluoromethyl radicals based on pulse radiolysis, laboratory scale experiments, and comparison of rates of reaction for analogous radical systems. In comparison to commercially available precursors, DMSO-F6 proved to be more stable, easier to handle and overall more convenient than leading F3C-reagents and may therefore be an ideal surrogate to study F3C radicals for time-resolved kinetics studies. In addition, we present an improved protocol for the preparation of this largely unexplored reagent.
- Santschi, Nico,Jelier, Benson J.,St?helin, Samuel,Nauser, Thomas
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supporting information
p. 9734 - 9742
(2019/12/02)
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- Inexpensive Radical Methylation and Related Alkylations of Heteroarenes
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A simple method for the introduction of a methyl and higher aliphatic group to various heteroarenes using very inexpensive reagents is described. It is based on the radical addition of a carboxylic xanthate followed by decarboxylation. Depending on the heteroarene structure, the decarboxylation can be spontaneous or induced by heating in N,N-dimethylacetamide or N-methyl pyrrolidone in a microwave oven.
- Huang, Qi,Zard, Samir Z.
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supporting information
p. 1413 - 1416
(2018/03/09)
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- Late-stage functionalization of biologically active heterocycles through photoredox catalysis
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The direct C-H functionalization of heterocycles has become an increasingly valuable tool in modern drug discovery. However, the introduction of small alkyl groups, such as methyl, by this method has not been realized in the context of complex molecule synthesis since existing methods rely on the use of strong oxidants and elevated temperatures to generate the requisite radical species. Herein, we report the use of stable organic peroxides activated by visible-light photoredox catalysis to achieve the direct methyl-, ethyl-, and cyclopropylation of a variety of biologically active heterocycles. The simple protocol, mild reaction conditions, and unique tolerability of this method make it an important tool for drug discovery.
- DiRocco, Daniel A.,Dykstra, Kevin,Krska, Shane,Vachal, Petr,Conway, Donald V.,Tudge, Matthew
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supporting information
p. 4802 - 4806
(2014/05/20)
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- Free Radical Carboxymethylation of Uracils with Benzoyl Peroxide in Acetic Acid
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Acetic acid solutions of the uracils and benzoyl peroxide were heated at 80 deg C to give 5-carboxymethyluracils.Similar treatment of caffeine and benzothiazole gave 8-methylcaffeine and 2-methylbenzothiazole, respectively.
- Itahara, Toshio,Ide, Naoko
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p. 1225 - 1226
(2007/10/02)
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- ADDITION OF ELECTROPHILIC RADICALS TO CAFFEINE: SYNTHETIC ASPECTS AND INFLUENCE OF THE PEROXIDIC INITIATORS
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Primary and secondary electrophilic radicals such as: .CHRCO2CH3 (R=H, CH3, CO2CH3) and tertiary .CCl3 radical were added directly at C-8 of, th model purine compound, caffeine to give the corresponding 8-substituted derivatives in fairly good yields.Unexpected reaction of caffeine with oxy radicals from the initiators (PhCO2., t-BuOO.) gave rise to C-5 substituted 1,3,7-trimethyl-5,7-dihydrouric acid derivatives (C-5-R=CCl3, CH3, C(CH3)2CO2CH3) and to the spirodihydantoin C-8 adduct derivative of caffeine 11.
- Zylber, J.,Ouazzani-Chahdi, L.,Lefort, D.,Chiaroni, A.,Riche, C.
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p. 721 - 732
(2007/10/02)
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- ISOMERIZATION AND DEALKYLATION OF METHYLATED XANTHINIUM DERIVATIVES
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The isomerization or dealkylation of methylated xanthinium derivatives takes place with the participation of nucleophiles and is facilitated in the presence of a sterically hindered configuration.When heated, 7,9-dimethyl- and 1,7,9-trimethylxanthinium salts isomerize to theobromine and caffeine respectively.Under these conditions 3,7,9-trimethyl- and 1,3,7,9-tetramethylxanthinium salts are dealkylated.The 1,7,9- and 3,7,9-trimethylxanthinium betaines are isomerized quantitatively to caffeine.The role of the nucleophile under these conditions is played by the negatively charged fragment in the pyridine part of molecule.An intermolecular mechanism of rearrangement of the 3,7,9-trimethylxanthinium betaine is demonstrated.The sterically overloaded 1,3,8,9-tetramethylxanthine and 1,3,9-trimethyl-8-azaxanthine and not the charged compounds undergo rearrangement.In these cases the nucleophilic center is the doubly bonded N7 atom in the five-membered ring.
- Muravich-Aleksandr, Kh. L.,Kolesova, M. B.,Pernikova, V. G.,Smirnova, N. V.
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p. 562 - 567
(2007/10/02)
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