Intramolecular Borylation via Sequential B−Mes Bond Cleavage for the Divergent Synthesis of B,N,B‐Doped Benzo[4]helicenes
作者:Julius A. Knöller、Guoyun Meng、Xiang Wang、David Hall、Anton Pershin、David Beljonne、Yoann Olivier、Sabine Laschat、Eli Zysman‐Colman、Suning Wang
DOI:10.1002/anie.201912340
日期:2020.2.17
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
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。