A method for the radical addition
toward N-tosylimines
based on light promoted C–H activation by tetrabutylammonium
decatungstate is described. The reaction proceeds under irradiation
using 400 nm light emitting diodes in conventional glassware. The
method can be applied for alkylations (cycloalkanes, ethers, dimethylformamide)
and acylation (primary aliphatic aldehydes) of both aromatic and aliphatic N-tosylimines.
A reaction of bromo- and iododifluoromethyl-substituted silanes with electron-deficient alkenes in the presence of an N-heterocyclic carbene borane complex is described. The reaction is performed under irradiation with light-emitting diodes and proceeds via a radical chain mechanism. The resulting products, the functionalized silicon reagents, can undergo chemoselective transformations involving either the silyldifluoromethyl fragment or the functional group.
A method for the addition of fluorinated groups to nitrones using an iridium photocatalyst and ascorbic acid as a stoichiometric reducing agent is described. The reaction proceeds through the generation of fluorinated radicals by single-electron reduction of fluorinated alkyl iodides with an iridium complex mediated by visible light. Besides perfluorinated reagents, partially fluorinated alkyl iodides can also be effectively used leading to the products, which cannot be obtained by conventional nucleophilic addition reactions. The resulting hydroxylamines can be readily converted to valuable fluorinated amines by reduction with zinc.
Reaction of thiols with α‐(trifluoromethyl)styrenes under photocatalytic conditions leading to desulfurative allylic fluorine substitution is described. The reaction is performed by treatment of thiols with benzyl zinc chloride to generate zinc thiolates followed by visible light induced desulfurization by means of triphenylphosphine. Radicals formed after the C−S bond cleavage react with the double bond affording gem‐difluorostyrenes.
A method for the reductive difluoroalkylation of electron-deficient alkenes using 1,1-difluorinated iodides mediated by irradiation with blue light is described. The reaction involves radical addition of 1,1-difluorinated radicals at the double bond followed by hydrogen atom transfer from sodium cyanoborohydride.
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