A 2,3-dihydro-1H-1,2-azaborole derivative 2 was converted to a cyclic (alkyl) (amino)carbene (cAAC) via 1,2-hydrogen migration triggered by boranes to afford cAAC-borane adducts. This procedure allowed us to develop an asymmetrical diborene cAAC·(Br)B═B(Br)·IDip 6, which was isolated and fully characterized. The 11B NMR spectrum, X-ray diffraction analysis and computational studies indicate that π-electrons on the central B2 moiety in 6 are unequivalently distributed, and thus polarized. A complete scission of the B═B double bond in 6 was achieved by the treatment with an isonitrile, which led to the formation of a base-stabilized B,N-containing methylenecyclopropane 7.

中文翻译：

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硼烷引起的烯烃-卡宾异构化：获得不对称二硼烯

2,3-二氢-1H-1,2-氮杂硼衍生物 2 通过硼烷引发的 1,2-氢迁移转化为环状（烷基）（氨基）卡宾 (cAAC)，以提供 cAAC-硼烷加合物。该程序使我们能够开发出不对称的二硼烯 cAAC·(Br)B=B(Br)·IDip 6，它被分离出来并被充分表征。11B NMR 光谱、X 射线衍射分析和计算研究表明，6 中中心 B2 部分上的 π 电子是不等价分布的，因此是极化的。通过用异腈处理实现了 6 中 B=B 双键的完全断裂，这导致形成碱稳定的含 B,N 的亚甲基环丙烷 7。