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A Vicinal Electrophilic Diborylation Reaction Furnishes Doubly Boron‐Doped Polycyclic Aromatic Hydrocarbons
Author(s) -
John Alexandra,
Bolte Michael,
Lerner HansWolfram,
Wagner Matthias
Publication year - 2017
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201701591
Subject(s) - fluoranthene , anthracene , chemistry , pyrene , chrysene , trimethylsilyl , boron , cycloalkane , polycyclic aromatic hydrocarbon , stille reaction , naphthalene , electrophile , aryne , benzene , photochemistry , perylene , dibenzothiophene , medicinal chemistry , organic chemistry , molecule , catalysis
Ten examples of unsymmetrically benzannulated, boron‐doped polycyclic aromatic hydrocarbons (B‐PAHs) were prepared by a one‐pot protocol using 4,5‐dichloro‐1,2‐bis(trimethylsilyl)benzene ( 1 ), BBr 3 , and selected PAHs—among them anthracene, benzo[ a ]pyrene, biphenylene, and fluoranthene. After mesitylation at the boron centers, the resulting air‐ and water‐stable products were investigated by 1 H/ 11 B{ 1 H}/ 13 C{ 1 H} NMR spectroscopy, X‐ray crystallography, cyclic voltammetry, and UV/Vis absorption/emission spectroscopy. The experiments were augmented by DFT calculations. Most of the B‐PAHs are brightly luminescent ( Φ PL up to 90 %) and undergo reversible reduction at moderate half‐wave potentials. The two chloro substituents of 1 are not only mandatory for accomplishing efficient diborylation, but can subsequently be used for Stille‐type coupling reactions to introduce 2‐thienyl moieties. Alternatively, Cl/H exchange is achievable with HSiEt 3 in a quantitative, Pd‐catalyzed transformation.