A regioselective carbosilylation of alkenes has emerged as a powerful strategy to access molecules with functionalized silylated alkanes, by incorporating silyl and carbon groups across an alkene double bond. However, to the best of our knowledge, organic fluorides have never been used in this protocol. Here we disclose the catalyst-free carbosilylation of alkenes using silyl boronates and organic fluorides mediated by tBuOK. The main feature of this transformation is the selective activation of the C-F bond of an organic fluoride by the silyl boronate without undergoing potential side-reactions involving C-O, C-Cl, heteroaryl-CH, and even CF3 groups. Various silylated alkanes with tertiary or quaternary carbon centers that have aromatic, hetero-aromatic, and/or aliphatic groups at the β-position are synthesized in a single step from substituted or non-substituted aryl alkenes. An intramolecular variant of this carbosilylation is also achieved via the reaction of a fluoroarene with a ω-alkenyl side chain and a silyl boronate.
We report a new protocol to form pentafluorosulfanyl (hetero)arenes via chlorine-fluorine exchange of (hetero)aryl tetrafluorosulfanyl chlorides by AgBF4. The method enables access to electron-deficient pentafluorosulfanyl(hetero)arenes, which are targets that are difficult to synthesize. Two advantages of AgBF4 are its ease of handling and stability. This would be a general transformation protocol.
Potassium-base-mediated defluoroetherification
of aryl and heteroaryl
fluorides with alkoxyboronic acid pinacol esters under transition-metal-free
conditions is reported. This protocol efficiently and safely provides
a wide variety of aryl ethers in high yields without using metal catalysts,
specific ligands, and harsh conditions to selectively forge Csp2–O bonds via the Csp2–F cleavage.
This method can be applied to the late-stage etherification of structurally
complex Csp2-fluorides and bioactive alcohols, such as
β-estradiol, calciferol, and tocopherol.
The defluorosilylation of aryl fluorides to access aryl silanes was achieved under transition-metal-free conditions via an inert C–F bond activation. The defluorosilylation, mediated by silylboronates and KOtBu, proceeded smoothly at room temperature to afford various aryl silanes in good yields. Although a comparative experiment indicated that Ni catalyst facilitated this transformation more efficiently, the transition-metal-free protocol is advantageous from a green chemistry perspective.
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