Intramolecular Borylation via Sequential B−Mes Bond Cleavage for the Divergent Synthesis of B,N,B-Doped Benzo[4]helicenes

Julius A. Knöller, Guoyun Meng, Xiang Wang, David Hall, Anton Pershin, David Beljonne, Yoann Olivier, Sabine Laschat, Eli Zysman-Colman, Suning Wang

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Abstract

New symmetric and unsymmetric B,N,B-doped benzo[4]helicenes 3–6 a/b have been achieved in good yields, using a three-step process, starting from N(tolyl)3 in a highly divergent manner (7 examples). A borinic acid functionalized 1,4-B,N-anthracene 1 was found to display unprecedented reactivity, acting as a convenient and highly effective precursor for selective formation of bromo-substituted B,N,B-benzo[4]helicenes 2 a/2 b via intramolecular borylation and sequential B−Mes bond cleavage in the presence of BBr3. Subsequent reaction of 2 a/2 b with Ar-Li provided a highly effective toolbox for the preparation of symmetrically/unsymmetrically functionalized B,N,B-helicenes. Their high photoluminescence quantum yields along with the small ΔEST suggest their potential as thermally activated delayed fluorescence (TADF) emitters for organic light-emitting diodes (OLEDs).

Original languageEnglish
Pages (from-to)3156-3160
Number of pages5
JournalAngewandte Chemie - International Edition
Volume59
Issue number8
DOIs
Publication statusPublished - 17 Feb 2020

Keywords

  • B,N,B-benzo[4]helicenes
  • boron
  • divergent synthesis
  • luminescence
  • synthetic methods

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