Nucleophilic Fluorination Reactions Starting from Aqueous Fluoride Ion Solutions

The sulfonium borane 2+ reacts with fluoride anions in MeOH/H2O mixtures to afford the zwitterionic fluoroborate 2-F as an easily isolable nonhygroscopic solid. In dry acetonitrile, 2-F reacts with PhS− to afford the anionic fluoroborate 1-F−. The latter is very labile and acts as a nucleophilic fluorination reagent toward a variety of substrates including alkylhalides and electron-deficient aromatic compounds. This approach may become broadly applicable to nucleophilic fluorination procedures that involve wet fluoride sources.

硼烷锍阳离子(2+)可在甲醇/水混合溶剂中与氟阴离子发生反应，生成两性离子型氟硼酸盐(2-F)，该产物为易于分离的非吸湿性固体。在无水乙腈中，2-F可与苯硫阴离子(PhS⁻)反应，生成阴离子型氟硼酸盐(1-F⁻)。该阴离子型氟硼酸盐稳定性极差，可作为亲核氟化试剂，适用于包括烷基卤化物与缺电子芳香族化合物在内的多种底物。此方法有望广泛应用于涉及含湿氟源的亲核氟化反应流程中。