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).

中文翻译：

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通过顺序B-Mes键断裂进行分子内硼化，以合成B，N，B掺杂的苯并[4]螺旋。

使用三步工艺，从N（甲苯基）3开始，以高度分散的方式，以高收率获得了新的对称和不对称的B，N，B掺杂的苯并[4]螺旋3-6 a / b（7例子）。发现硼酸官能化的1,4-B，N-蒽1显示出前所未有的反应活性，可作为选择性形成溴取代的B，N，B-苯并[4]螺旋烯2 a /的便捷高效前体。在存在BBr 3的情况下，通过分子内的硼酸化和顺序的B-Mes键裂解，图2b所示。随后2 a / 2 b与Ar-Li的反应为制备对称/不对称官能化的B，N，B-螺旋烯提供了一个高效的工具箱。