Heterocycle-tethered organoboranes generally dimerize by using the heteroatom present in them. When this does not take place, some interesting molecules or properties are bound to be observed. This is demonstrated in this work, as well. The lithium salt of 1,2-dimethylimidazole reacts with Et₂B(OMe) or 9-BBN-OMe to give the air-stable intermolecular adduct of 2-(dialkylborylmethyl)-1-methylimidazole (alkyl = Et (1) and 9-BBN (2)) after treatment with BF₃·OEt₂. These two dimers exist in two stereoisomers: clockwise and counterclockwise, as shown by their X-ray structures. On the contrary, in the analogous reaction between the lithium salt of 1,3,5-trimethylpyrazole and Et₂B(OMe) in the presence of BF₃·OEt₂, an air- and moisture-sensitive adduct, 1-(diethylborylmethyl)-3,5-dimethylpyrazole·BF₂(OMe) (3), was isolated as a liquid in an excellent yield, instead of its dimer. Its structure is based on ¹H, ¹⁹F, ¹¹B, and HRMS methods and supported by anion binding studies. Consequently, the reactive neat liquid 3 decomposes in air to give the bicyclo[3.3.1]nonane-like neutral bicycle 4. Notably, a CH₂Cl₂ solution of 3 decomposes differently to give the OH-bridged cationic analogous bicycle 5. In addition, their precursors, [2-(diethylborylmethyl)-1-methylimidazole·LiOMe(1,2-dimethylimidazole)]₂ 6, [(1-(diethylborylmethyl)-3,5-dimethylpyrazole·LiOMe)₂THF] 7, and [(1-(diethylborylmethyl)-3,5-dimethylpyrazole·LiOMe(DMAP)₂] 8, were also isolated and structurally characterized. In the crystal lattices of structures of 4, 5, and 7, both enantiomers RR and SS are present.

中文翻译：

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杂环系硼烷及其前体的合成，反应和结构

杂环束缚的有机硼烷通常通过使用它们中存在的杂原子来二聚。当这种情况不发生时，必定会观察到一些有趣的分子或特性。这项工作也证明了这一点。1,2-二甲基咪唑锂盐与Et ₂ B（OMe）或9-BBN-OMe反应生成2-（二烷基硼基甲基）-1-甲基咪唑的空气稳定的分子间加合物（烷基= Et（1）和9 -BBN（2））用BF ₃ ·OEt _2处理后。这两个二聚体以两种立体异构体形式存在：顺时针和逆时针，如其X射线结构所示。相反，在1,3,5-三甲基吡唑锂盐与Et ₂之间的类似反应中在BF ₃ ·OEt ₂的存在下分离B（OMe），在空气中分离出对空气和湿气敏感的加合物1-（二乙基硼基甲基）-3,5-二甲基吡唑·BF ₂（OMe）（3）。出色的产量，而不是其二聚体。其结构基于¹ H，¹⁹ F，¹¹ B和HRMS方法，并得到阴离子结合研究的支持。因此，反应性纯净液体3在空气中分解，得到双环[3.3.1]壬烷类中性自行车4。值得注意的是，一个CH ₂氯₂的溶液3级中分解不同，得到OH-桥接阳离子类似自行车5。另外，它们的前体是[2-（二乙基硼基甲基）-1-甲基咪唑·LiOMe（1,2-二甲基咪唑）] ₂ 6，[（1-（二乙基硼基甲基）-3,5-二甲基吡唑·LiOMe）₂ THF] 7，和[（1-（diethylborylmethyl）-3,5-二甲基吡唑·LiOMe（DMAP）₂ ] 8，也分离和结构表征。在结构的晶格4，5，和7，两种对映体的RR和SS是展示。