Zinc‐Mediated Intermolecular Reductive Radical Fluoroalkylsulfination of Unsaturated Carbon–Carbon Bonds with Fluoroalkyl Bromides and Sulfur Dioxide

Abstract

A versatile and general zinc‐mediated intermolecular reductive radical fluoroalkylsulfination of unsaturated C−C bonds has been developed using readily available fluoroalkyl bromides and 1,4‐diazabicyclo[2.2.2]octane‐bis(sulfur dioxide) adduct (DABSO) with wide substrate scope and excellent functional group tolerance. Sulfur dioxide anion radical generated in situ from the reduction of sulfur dioxide with zinc may be involved in the reaction mechanism.

Mn-Enabled Radical-Based Alkyl–Alkyl Cross-Coupling Reaction from 4-Alkyl-1,4-dihydropyridines

“…Interestingly, the cross-coupling product 3 was obtained in 51% yield when the reactions were carried out under standard reaction conditions. These result may indicate that the in situ-generated Mn­(I) would coordinate with the olefin to accelerate the radical addition reaction …”

Promising reagents for difluoroalkylation

“…[116][117][118] In 2019, Chen and coworkers achieved a zinc-mediated intermolecular reductive radical fluoroalkylsulfination of unsaturated C-C bonds with fluoroalkyl bromides and DABSO (Scheme 47). 119 Alkenes and alkynes were all tolerated in this reaction, affording the product with moderate yields. Preliminary mechanistic investigations revealed that a sulfur dioxide anion radical species reduced by Zn from SO 2 was involved in this reaction.…”

Fluoroalkanesulfinate Salts as Dual Fluoroalkyl and SO2 Sources: Atom-Economical Fluoroalkyl-Sulfonylation of Alkenes and Alkynes by Photoredox Catalysis

“…In addition, the fluoroalkyl group to be introduced is limited to the CF 3 group because of structural limitations of the above-mentioned precursor. More recently, external addition of a SO 2 source such as bis­(sulfur dioxide)–1,4-diazabicyclo[2.2.2]­octane adduct (DABSO) has extended accessible fluoroalkyl groups and alkenes in addition to the CF 3 group and aliphatic alkenes, but this is not an atom-economical strategy . During preparation of the present Letter, the Liao group reported an electrochemical method for cascade-type trifluoromethyl-sulfonylation of N -cyanamide alkenes with 1a .…”