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Updated: Apr 20, 2026

Efficient Synthesis of All-Carbon Quaternary Centers via the Conjugate Addition of Functionalized Monoorganozinc Bromides
Published on: May 26, 2019
[Synthesis of hypervalent organo-λ(3)-bromanes and their reactions by using leaving group ability of λ(3)-bromanyl
1Graduate School of Pharmaceutical Sciences, The University of Tokyo.
Abstract:
Hypervalent organo-λ(3)-iodanes have attracted great interest in organic synthesis; however, the chemistry of hypervalent organo-λ(3)-bromanes remains largely unexplored, mainly because of synthetic difficulties. Iodobenzene is readily oxidized by common oxidants such as peracids under mild conditions, whereas bromobenzene is inert. Since the ionization potential of bromobenzene (8.98 eV) is higher than that of iodobenzene (8.69 eV), hypervalent-λ(3)-bromane would show much higher reactivity. We overcame this problem by using difluoro(aryl)-λ(3)-bromane (Frohn's reagent), which serves as a pivotal progenitor of various λ(3)-bromanes including imino-λ(3)-bromane, cyclopent-1-enyl-λ(3)-bromane, (E)-β-alkylvinyl-λ(3)-bromane, and diacetoxy-λ(3)-bromane. These reagents possess highly unusual reactivity based on the enormously enhanced nucleofugality of the aryl-λ(3)-bromanyl group.
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