General alkyl fluoride functionalization via short-lived carbocation-organozincate ion pairs.

Lucas Kane, D; Figula, Bryan C; Balaraman, Kaluvu; Bertke, Jeffery A; Wolf, Christian · Nat Commun · 2024

basic_science · Level V

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Abstract

Fluorinated organic compounds are frequently used across the chemical and life sciences. Although a large, structurally diverse pool of alkyl fluorides is nowadays available, synthetic applications trail behind the widely accepted utility of other halides. We envisioned that C(sp<sup>2</sup>)-C(sp<sup>3</sup>) cross-coupling reactions of alkyl fluorides with fluorophilic organozinc compounds should be possible through a heterolytic mechanism that involves short-lived ion pairs and uses the stability of the Zn-F bond as the thermodynamic driving force. This would be mechanistically different from previously reported radical reactions and overcome long-standing limitations of organometallic cross-coupling methodology, including competing β-hydride elimination, homodimerization and hydrodefluorination. Here, we show a practical C<sub>sp3</sub>-F bond functionalization method that expands the currently restricted synthetic space of unactivated primary, secondary and tertiary C(sp<sup>3</sup>)-F bonds but also uses benzylic, propargylic and acyl fluorides. Many functional groups and sterically demanding substrates are tolerated, which allows practical carbon-carbon bond formation and late-stage functionalization.