1. Photochemical Intramolecular C−H Addition of Dimesityl(hetero)arylboranes through a [1,6]-Sigmatropic Rearrangement.
- Author
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Ando, Naoki, Fukazawa, Aiko, Kushida, Tomokatsu, Shiota, Yoshihito, Itoyama, Shuhei, Yoshizawa, Kazunari, Matsui, Yasunori, Kuramoto, Yutaro, Ikeda, Hiroshi, and Yamaguchi, Shigehiro
- Subjects
AROMATIC compounds ,CHEMICAL reactions ,ARYL group ,PHOTOLYSIS (Chemistry) ,PHOTOCHEMISTRY - Abstract
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). [ABSTRACT FROM AUTHOR]
- Published
- 2017
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