- Selective C-F bond activation: Substitution of unactivated alkyl fluorides using YbI3
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F makes the break: The carbon-fluorine single bond is quite strong, thus making aliphatic C-F bond scission unusually challenging. A new methodology utilizing YbI3 leads to the conversion of a C-F bond into a C-I bond, and is compatible with various functional groups. The reaction is exceptionally selective towards alkyl fluorides and proceeds under mild conditions. Copyright
- Traeff, Annika M.,Janjetovic, Mario,Ta, Linda,Hilmersson, Goeran
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supporting information
p. 12073 - 12076
(2013/12/04)
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- Reactions of 1,3-Dihaloadamantanes with Carbanions in DMSO: Ring-Opening Reactions to Bicyclo[3.3.1]nonane Derivatives by the SRN1 Mechanism
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The reactions of 1,3-dihaloadamantanes with various carbanionic nucleophiles were studied. Potassium enolates of acetophenone (2) and pinacolone (10b) and the anion of nitromethane (10a) reacted with 1,3-diiodoadamantane (1a) in DMSO under photostimulation by a free radical chain process to form a 1-iodo monosubstitution product as an intermediate, which undergoes concerted fragmentation to form derivatives of 7-methylidenebicyclo[3.3.1]nonene (3 and 11). This reaction does not occur in the dark at 25 °C, and the photostimulated reaction is partially inhibited by p-dinitrobenzene. 1,3-Dibromoadamantane (1b) and 1-bromo-3-chloroadamantane (1c) also reacted under irradiation with 2, although more sluggish than 1a, also giving the 7-methylidenebicyclo-[3.3.1]nonene derivative 3. When a nucleophile was used without acidic hydrogens in the α-position, such as the enolate ion of isobutyrophenone (16), in order to inhibit the ring opening of adamantane, it reacted under irradiation with 1a to give the products adamantane, 1-iodoadamantane, monosubstituted 17, 1-iodo-monosubstituted 19, and disubstituted 20. Their distribution depended on the experimental conditions. In these reactions, 1-iodoadamantane and 19 were intermediates. For reactions involving the radical anion intermediate of the 1-iodo monosubstitution product, the intermolecular ET to the substrate was observed to be much faster than intramolecular ET to the C-I bond.
- Lukach, Andres E.,Santiago, Ana N.,Rossi, Roberto A.
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p. 4260 - 4265
(2007/10/03)
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- Mechanistic Definition of Trimethylstannylation of 1,3-Dihaloadamantanes: Delocalized Radical Anions as Possible Intermediates
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A series of 1,3-dihaloadamantanes (3, X = Y = halogens) have been synthesized, characterized, and treated with (trimethylstannyl) alkali reagents (Me3SnM, M = Li or Na) in the absence and presence of tert-butylamine (TBA) and dicyclohexylphosphine (DCPH).The product distributions of these reactions have been established by 13C and 119Sn NMR spectroscopy and vapour-phase chromatographic analyses.The substitution via an SRN1-type pathway is shown to be a significant reaction for several of the derivatives of 3 (X = F, Y = Br or I; X = Cl, Y = Br or I; X = Y = Br) but not for the bromo iodide or diiodide (3, X = Br, Y = I and X = Y =I).For the latter two compounds, the formation of 1,3-dehydroadamantane or propellane 8 is the predominant reaction product while tin substitution is insignificant.Propellane 8 formation is also a significant reaction product for some of the other dihalo derivatives of 3 (X = Cl, Y = I and X = Y = Br) but not for others (3, X = F, Y = Br or I and X = Cl, Y = Br).The mechanism of formation of 8 is perplexing in light of the trapping experiments in the presence of TBA and DCPH.A possible pathway is proposed in wich the key intermediate is a delocalized radical anion.
- Adcock, William,Clark, Christopher I.
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p. 7341 - 7349
(2007/10/02)
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