Selective Synthesis of Stannoles by 1,1‐Carboboration of Bis(trimethylsilylethynyl)tin Compounds Using Weakly and Strongly Electrophilic Triorganoboranes: Characterization of a Zwitterionic Intermediate
Selective Synthesis of Stannoles by 1,1‐Carboboration of Bis(trimethylsilylethynyl)tin Compounds Using Weakly and Strongly Electrophilic Triorganoboranes: Characterization of a Zwitterionic Intermediate
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DOI：
10.1002/ejic.201400028
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发表时间：
2014-04
影响因子：
2.3
通讯作者：
B. Wrackmeyer;P. Thoma;S. Marx;Tobias A Bauer;R. Kempe
中科院分区：
文献类型：
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作者：
B. Wrackmeyer;P. Thoma;S. Marx;Tobias A Bauer;R. Kempe
三有机硼烷BEt3、BPh3和B(C6F5)3与双(三甲基硅乙炔)二有机锡化合物[R12Sn(C≡C-SiMe3)2；R12=-(CH2)5-(A)，R1=nBu(B)，noct(C)，Ph(D)]反应，选择性地、定量地得到锡内酯。反应分分子间和分子内两步进行，中间产物用核磁共振谱进行检测。在一种情况下，使用强亲电性的B(C6F5)3，分离出一种两性离子中间体，并通过X-射线衍射分析对其结构进行了表征。讨论了1，1-碳硼化反应的可逆性问题。用多核核磁共振波谱(1H、11B、13C、19F、29Si、119Sn核磁共振)对中间体和最终产物锡烯进行了表征。利用优化的气相几何构型，用密度泛函方法计算了中间体的部分核磁共振参数(11B、13C、29Si)。
The triorganoboranes BEt3, BPh3, and B(C6F5)3 were allowed to react with bis(trimethylsilylethynyl)diorganotin compounds [R12Sn(C≡C–SiMe3)2; R12 = –(CH2)5– (a), R1 = nBu (b), nOct (c), Ph (d)] to give selectively and quantitatively stannoles. The reactions proceeded by 1,1-carboboration in two consecutive steps (inter- and intramolecular) and intermediates were detected by NMR spectroscopy. In one case, using the strongly electrophilic B(C6F5)3, a zwitterionic intermediate was isolated and structurally characterized by X-ray diffraction analysis. The question of reversibility of the 1,1-carboboration is addressed. Multinuclear magnetic resonance spectroscopy (1H, 11B, 13C, 19F, 29Si, 119Sn NMR) was used to characterize the intermediates and the stannoles as the final products. Some of the NMR parameters (11B, 13C, 29Si) of the intermediates were calculated by DFT methods using the optimized gas-phase geometries.