Silver-Mediated Radical Fluorination And Trifluoromethylthiolation

Fluorine-containing compounds have been widely used in pharmaceuticals, agrochemicals and materials because of their unique lipophilicity and bioactivities. We reported here a silver-catalyzed decarboxylative fluorination of various aliphatic carboxylic acids with selectfluor reagent in aqueous solution, a silver-mediated oxidative aryltrifluoromethylthiolation of activated alkenes to produce valuable trifluoromethylthiolated oxindoles, and a Pd-catalyzed C-H trifluromethylthiolation via a trifluoromethylthiol radical oxidation of palladiumcycle generated from C-H activation.This dissertation includes four chapters.Chapter1:Research progress of C-F and C-SCF3bonds formations For the introduction of fluorine atom, we reviewd recent C(sp2)-F and C(sp3)-F bonds foramtions, especially for Pd, Ag-catalyzed or-mediated reactions, and the radical fluorination methods. For the introduction of SCF3, we reviewed the progress of direct nucleophilic and electrophilic trifluoromethylthiolation developed in recent years.Chapter2:Silver-catalyzed decarboxylative fluorination of aliphatic carboxylic acids in aqueous solutionSite-specific C(sp3)-F bond formations are still a challenging task. We developed here a Ag-catalyzed decarboxylative fluorination of aliphatic carboxylic acids with selectfluor reagent in aqueous solution, affording various alkyl fluorides in satisfactory yields under mild conditions. This efficient radical fluorination method shows good chemoselectivity and functional-group tolerance. A mechanism involvinig Ag(Ⅲ)-mediated single electron transfer followed by fluorine atom transfer is proposed for this catalytic fluorodecarboxylation.Chapter3:Silver-mediated radical aryltrifluoromethylthiolaton of activated alkenesAlthough a diverse array of organic molecules were trifluoromethylthiolated by the nucleophilic and electrophilic CF3S reagents, the F3CS· radical-type pathway remains less explored. We developed the first example of silver-mediated oxidative aryltrifluoromethylthiolation of activated alkenes to produce valuable trifluoromethylthiole-containing oxindoles. Mechanistic investigations indicated that this novel transformation proceeded through a unique F3CS· radical addition path, thus providing a practical and easy-handling method to generate a F3CS· radical in the laboratory.Chapter4:Ag-mediated Pd-catalyzed radical C-H trifluoromethylthiolation of2-phenylpyridineWith the new silver-mediated trifluoromethylthio radical-generating method, we developed a palladium-catalyzed C-H trifluoromethylthiolation via C-SCF3reductive elimination from high valent Pd species, which formed through the trifluoromethylthio radical oxidation of cyclopalladium after the C-H activation. Different from the previous report on copper-mediated C-H trifluoromethylthiolation, this newly developd method could furnish mono-substituted products.