Photochemical Intramolecular C−H Addition of Dimesityl(hetero)arylboranes through a [1,6]-Sigmatropic Rearrangement

Naoki Ando, Aiko Fukazawa, Tomokatsu Kushida, Yoshihito Shiota, Shuhei Itoyama, Kazunari Yoshizawa, Yasunori Matsui, Yutaro Kuramoto, Hiroshi Ikeda, Shigehiro Yamaguchi

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


A new reaction mode for triarylboranes under photochemical conditions was discovered. Photoirradiation of dimesitylboryl-substituted (hetero)arenes produced spirocyclic boraindanes, where one of the C−H bonds in the ortho-methyl groups of the mesityl substituents was formally added in a syn fashion to a C−C double bond of the (hetero)aryl group. Quantum chemical calculations and laser flash photolysis measurements indicated that the reaction proceeds through a [1,6]-sigmatropic rearrangement. This behavior is reminiscent of the photochemical reaction mode of arylalkenylketones, thus demonstrating the isosteric relation between tricoordinate organoboron compounds and the corresponding pseudo-carbocationic species in terms of pericyclic reactions. Despite the disrupted π-conjugation, the resulting spirocyclic boraindanes exhibited a characteristic absorption band at relatively long wavelengths (λ=370—400 nm).

Original languageEnglish
Pages (from-to)12210-12214
Number of pages5
JournalAngewandte Chemie - International Edition
Issue number40
Publication statusPublished - Sept 25 2017

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)


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