Cu(OTf)₂‑Mediated Fluorination of Aryltrifluoroborates with Potassium Fluoride

This Communication describes the Cu­(OTf)₂-mediated fluorination of aryltrifluoroborates with KF. The reaction proceeds under mild conditions (at 60 °C over 20 h) and shows a broad substrate scope and functional group tolerance. The Cu is proposed to play two separate roles in this transformation: (1) as a mediator for the aryl–F coupling and (2) as an oxidant for accessing a proposed Cu^III(aryl)­(F) intermediate

Acyl Azolium Fluorides for Room Temperature Nucleophilic Aromatic Fluorination of Chloro- and Nitroarenes

The reaction of acid fluorides with <i>N</i>-heterocyclic carbenes (NHCs) produces anhydrous acyl azolium fluorides. With appropriate selection of acid fluoride and NHC, these salts can be used for the room temperature S_NAr fluorination of a variety of aryl chlorides and nitroarenes

Anhydrous Tetramethylammonium Fluoride for Room-Temperature S_NAr Fluorination

This paper describes the room-temperature S_NAr fluorination of aryl halides and nitroarenes using anhydrous tetramethylammonium fluoride (NMe₄F). This reagent effectively converts aryl-X (X = Cl, Br, I, NO₂, OTf) to aryl-F under mild conditions (often room temperature). Substrates for this reaction include electron-deficient heteroaromatics (22 examples) and arenes (5 examples). The relative rates of the reactions vary with X as well as with the structure of the substrate. However, in general, substrates bearing X = NO₂ or Br react fastest. In all cases examined, the yields of these reactions are comparable to or better than those obtained with CsF at elevated temperatures (i.e., more traditional halex fluorination conditions). The reactions also afford comparable yields on scales ranging from 100 mg to 10 g. A cost analysis is presented, which shows that fluorination with NMe₄F is generally more cost-effective than fluorination with CsF