O-(Dihydrosilyl)(dimesitylboryl)benzenes1 were prepared in 6 steps. o-Dibromobenzene was mono-lithiated with n-BuLi and reacted with chloro(dimethoxy)silanes to afford o-C6H4(Br)[SiR(OMe)2] (2) (R = Ph, Me). Bromine–lithium exchange between 2 and tert-BuLi produced o-C6H4(Li)[SiR(OMe)2] (3), which were reacted with fluoro(dimesityl)borane to give o-C6H4(BMes2)[SiR(OMe)2] (4). Reduction of 4 with LiAlH4 in THF
以6个步骤制备O-(二氢甲硅烷基)(二甲磺基)苯1。邻-二溴苯与正丁基锂单片化,并与氯(二甲氧基)硅烷反应,得到邻-C 6 H 4(Br)[SiR(OMe)2 ](2)(R = Ph,Me)。溴-锂在2和叔丁基锂之间的交换产生了o -C 6 H 4(Li)[SiR(OMe)2 ](3),将其与氟硼烷(dimesityl )硼烷反应生成o -C 6 H 4(BMes)2)[SiR(OMe)2 ](4)。用LiAlH 4在THF中还原4得到[ o -C 6 H 4(BMes 2 H)(SiRH 2)] - Li +(thf)n(9)。用BF 3 OEt 2处理9得到目标化合物1。1的结构通过NMR光谱和X射线晶体学分析确定。
Intramolecular HAr Ligand Exchange between Silicon and Boron: Functionality Transfer of SiH to BH
o‐C6H4(SiR3−nHn)(BMes2) (1; R=Me, Ph; n=1, 2) undergo MesH (Mes=mesityl) ligand exchange between the silicon atom and the boron atom to form o‐C6H4(SiMesR3−nHn−1)(BMesH) (6) upon heating. The resulting hydroborane intermediates (6) immediately react with benzaldehyde to afford their corresponding benzyloxyboranes (5). A DFT study of model compounds reveals the transition states of the ligand exchange
ø -C 6 ħ 4(SIR 3 - ñ ħ Ñ)(BMES 2)(1 ; R = Me中的Ph值; Ñ = 1,2)经历的Mes H(的Mes =异亚丙基丙酮)中的硅原子和配位体之间交换硼原子在加热时形成o ‐ C 6 H 4(SiMesR 3 − n H n − 1)(BMesH)(6)。生成的氢硼烷中间体(6)立即与苯甲醛反应,得到其相应的苄氧基硼烷(5)。DFT对模型化合物的研究揭示了配体交换的过渡态。硼中心从硅原子中提取氢化物是达到过渡态的关键,其中包括三配位的甲硅烷基阳离子部分和四配位的硼氢化物部分。