Metal-free dehydropolymerisation of phosphine-boranes using cyclic (alkyl)(amino)carbenes as hydrogen acceptors
Metal-free dehydropolymerisation of phosphine-boranes using cyclic (alkyl)(amino)carbenes as hydrogen acceptors
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DOI：
10.1038/s41467-019-08967-8
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发表时间：
2019-03
影响因子：
16.6
通讯作者：
Nicola L Oldroyd;S. Chitnis;Vincent T. Annibale;Marius I. Arz;H. Sparkes;I. Manners
中科院分区：
文献类型：
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作者：
Nicola L Oldroyd;S. Chitnis;Vincent T. Annibale;Marius I. Arz;H. Sparkes;I. Manners
环（烷基）（氨基）卡宾（CAAC）中的二价卡宾碳中心具有类似过渡金属的插入E-H σ-键（E = H，N，Si，B，P，C，O）的能力，并形成新的强C-E和C-H键。虽然随后的产品转化代表了一个有吸引力的策略，无金属合成，很少的例子已经报道。本文描述了在温和条件下，CAAC作为化学计量的氢受体，使膦硼烷RR'PH·BH 3脱氢，释放出单体膦硼烷[RR' PBH 2]。后一种物质是短暂的中间体，其或者聚合成相应的聚膦硼烷[RR'PBH 2]n（R = Ph; R' = H、Ph或Et），或者以CAAC-膦硼烷加合物CAAC·H2 BPRR '（R = R' =tBu; R = R' = Mes）的形式被捕获。与先前建立的方法如仅产生P-单取代的聚合物[RHBH 2]n的过渡金属催化的脱氢偶联相反，CAAC介导的途径还提供了获得P-二取代的聚合物[RR'PBH 2]n（R = Ph; R' = Ph或Et）的途径。
The divalent carbene carbon centre in cyclic (alkyl)(amino)carbenes (CAACs) is known to exhibit transition-metal-like insertion into E–H σ-bonds (E = H, N, Si, B, P, C, O) with formation of new, strong C–E and C–H bonds. Although subsequent transformations of the products represent an attractive strategy for metal-free synthesis, few examples have been reported. Herein we describe the dehydrogenation of phosphine-boranes, RR’PH·BH3, using a CAAC, which behaves as a stoichiometric hydrogen acceptor to release monomeric phosphinoboranes, [RR’PBH2], under mild conditions. The latter species are transient intermediates that either polymerise to the corresponding polyphosphinoboranes, [RR’PBH2]n(R = Ph; R’ = H, Ph or Et), or are trapped in the form of CAAC-phosphinoborane adducts, CAAC·H2BPRR’ (R = R’ =tBu; R = R’ = Mes). In contrast to previously established methods such as transition metal-catalysed dehydrocoupling, which only yield P-monosubstituted polymers, [RHPBH2]n, the CAAC-mediated route also provides access to P-disubstituted polymers, [RR’PBH2]n(R = Ph; R’ = Ph or Et).