六甲基苯的消除使得能够生成瞬态的、空间位阻不受阻碍的多键硼物种。
Hexamethylbenzene elimination enables the generation of transient, sterically unhindered multiply bonded boron species.
作者信息
Zhang Chonghe, Dabringhaus Philipp, Tra Bi Youan E, Gilliard Robert J, Cummins Christopher C
机构信息
Department of Chemistry, Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA
出版信息
Chem Sci. 2025 May 19. doi: 10.1039/d5sc02645h.
We present a method for the generation of boron-containing unsaturated small molecules hexamethylbenzene elimination. The fragmentation precursors are obtained through bond insertion into phenyl boranorbornadiene (PhB(CMe), 1). Compound 1 undergoes 1,1-insertion with 2,6-xylyl isocyanide, affording a boron-doped bicyclo[2.2.2]octa-2,5-diene 2. Heating 2 in toluene results in the formation of a base-stabilized boraketenimine PhB(CNxyl) (, borylene diisocyanide) as an intermediate retro-Diels-Alder reaction. Surprisingly, PhB(CNxyl) dimerizes to give a boron-doped 6-membered ring (PhB)C(CNxyl)4. The reaction of 1 with trimethylamine -oxide and phenyl azide yields triphenyl boroxine and a BN ring, respectively, implying the involvement of transient oxoborane (PhB[triple bond, length as m-dash]O) and iminoborane intermediates (PhB[triple bond, length as m-dash]NPh), respectively. Furthermore, boranorbornadiene also undergoes 2,3-insertion with mesityl isocyanate (MesNCO), affording a fused 6/5-membered heterocycle 11. This insertion profile is analogous to the insertion of phenyl azide into 1.
我们提出了一种通过六甲基苯消除反应生成含硼不饱和小分子的方法。通过将键插入苯基硼降冰片二烯（PhB(CMe)，1）来获得裂解前体。化合物1与2,6-二甲基苯基异氰酸酯发生1,1-插入反应，得到硼掺杂的双环[2.2.2]辛-2,5-二烯2。在甲苯中加热2会导致形成一种碱稳定的硼杂乙烯亚胺PhB(CNxyl)（，硼烯二异氰酸酯）作为逆狄尔斯-阿尔德反应的中间体。令人惊讶的是，PhB(CNxyl)二聚生成一个硼掺杂的六元环(PhB)C(CNxyl)4。1与三甲胺氧化物和苯基叠氮化物的反应分别生成三苯基硼酸酯和一个BN环，这分别意味着涉及瞬态氧硼烷（PhB[三键，长度用m破折号表示]O）和亚氨基硼烷中间体（PhB[三键，长度用m破折号表示]NPh）。此外，硼降冰片二烯也与均三甲苯基异氰酸酯（MesNCO）发生2,3-插入反应，得到一个稠合的6/5元杂环11。这种插入模式类似于苯基叠氮化物插入1的情况。
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