Light-induced iodoperfluoroalkylation reactions of carbon-carbon multiple bonds in water

In this work we have undertaken the radical-induced addition of 1-iodo-n-perfluorobutane onto electron-rich alkenes, alkenes with electron withdrawing groups, and alkynes in water, initiated photochemically. The lack of hydrogen donor (i.e.: (Me 3Si) 3SiH) in our reaction medium facilitates a Halogen Atom-transfer reaction (HAT), affording the respective perfluorobutylated alkyl and alkenyl halides (iodides) in good yields in water. We have also found that water exerts a relevant solvent effect on the rates of perfluoroalkyl radical additions onto double and triple bonds. The stereoselectivity of the radical addition reaction of alkynes is studied. The novelty of this work relies on the photochemical generation of fluorinated radicals in water, and the Halogen Atom-transfer addition reactions of iodoperfluoroalkanes onto carbon-carbon unsaturated bonds in water induced by light.Fil: Slodowicz, Mariel Pamela. Universidad de Belgrano; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Barata Vallejo, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Orgánica; ArgentinaFil: Vázquez, A.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Orgánica; ArgentinaFil: Sbarbati Nudelman, N.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Orgánica; ArgentinaFil: Postigo, Jose Alberto. Universidad de Belgrano; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Solvent and Ligand Effects on the Tandem Addition-Lithiation- Electrophilic Substitution of Phenyllithium on α,β-Unsaturated Carbonyl Compounds †

Abstract: The reaction of phenyllithium with E-cinnamaldehyde is extremely sensitive to the reaction conditions and surprising changes in the product distribution were observed upon changes in the solvent, concentrations, duration or temperature of the reaction. For these reasons the above mentioned reaction was considered an appropriate model to examine solvent and aggregation effects of PhLi. On the other hand, when two or trhee equiv of phenyllithium are used, instead of one, the reaction transforms into a surprising tandem addition-lithiation-β-alkylation sequence, that can be successfully applied to the synthesis of substituted dihydrochalcones. The observed effects upon changes in the reaction conditions, as well as the effects of additives that modify the PhLi dimer-monomer equilibrium are consistent with a reaction pathway in which dimeric phenyl lithium attacks to the E-cinnamaldehyde without previous deaggregation. Usually, monomers are found to be more reactive than dimers, but, in this reaction the opposite effect is observed, and the tandem reaction spectacularly decreases with the (PhLi)2 concentration