Kawaguchi Himeko, Fuse Kotomi, Maeda Nanoka, Kuwabara Takuya
Department of Chemistry and Biochemistry, Graduate School of Humanities and Sciences, Ochanomizu University, 2-1-1, Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan.
Molecules. 2024 Aug 25;29(17):4024. doi: 10.3390/molecules29174024.
The general synthesis of boron-containing cyclic compounds (boracycles) necessitates toxic organotin precursors or highly reactive boron halides. Here, we report the synthesis of seven- and five-membered boracycles utilizing arylboronic acid pinacol esters (ArBpins) as stable boron sources. Grignard reagents generated from 2,2'-dibromodibenzyl or 2,2'-dibromobiphenyl reacted with ArBpins, where Ar = 9-anthryl (Anth), 2,4,6-trimethylphenyl (Mes), or 2,4,6-triisopropylphenyl (Tip), to give 10,11-dihydro-5-dibenzo[,]borepins or dibenzoborole derivatives. This Bpin-based method was successfully applied to a one-shot double boracycle formation, providing a dihydrodibenzoborepin-anthracene-dihydrodibenzoborepin triad molecule in a good yield. The dihydrodibenzoborepin bearing the Anth group was directly converted to the unsaturated borepin by NBS/AIBN. All products were characterized by NMR, HRMS, and in some cases, single-crystal X-ray diffraction analysis. Additionally, the photophysical properties of the products are also reported.
含硼环状化合物（硼杂环）的一般合成需要使用有毒的有机锡前体或高反应性的硼卤化物。在此，我们报道了利用芳基硼酸频哪醇酯（ArBpins）作为稳定的硼源来合成七元环和五元环硼杂环。由2,2'-二溴二苄基或2,2'-二溴联苯生成的格氏试剂与ArBpins反应，其中Ar = 9-蒽基（Anth）、2,4,6-三甲基苯基（Mes）或2,4,6-三异丙基苯基（Tip），得到10,11-二氢-5-二苯并[，]硼环庚三烯或二苯并硼咯衍生物。这种基于Bpin的方法成功应用于一次性形成双硼杂环，以良好的产率提供了二氢二苯并硼环庚三烯-蒽-二氢二苯并硼环庚三烯三联体分子。带有Anth基团的二氢二苯并硼环庚三烯通过NBS/AIBN直接转化为不饱和硼环庚三烯。所有产物均通过NMR、HRMS进行表征，在某些情况下还通过单晶X射线衍射分析进行表征。此外，还报道了产物的光物理性质。
