Horsley Downie Thomas M, Charman Rex S C, Hall Jonathan W, Mahon Mary F, Lowe John P, Liptrot David J
Department of Chemistry, University of Bath. Claverton Down, Bath, BA2 7AY, UK.
Dalton Trans. 2021 Nov 16;50(44):16336-16342. doi: 10.1039/d1dt03540a.
Reaction of bis(pinacolato)diboron with (6-Dipp)CuOBu generates a ring-expanded N-heterocyclic carbene supported copper(I) boryl, (6-Dipp)CuBpin. This compound showed remarkable stability and was characterised by NMR spectroscopy and X-ray crystallography. (6-Dipp)CuBpin readily dechalcogenated a range of heterocumulenes such as CO, isocyanates and isothiocyanates to yield (6-Dipp)CuXBpin (X = O, S). In the case of CO catalytic reduction to CO is viable in the presence of excess bis(pinacolato)diboron. In contrast, in the case of iso(thio)cyanates, the isocyanide byproduct of dechalcogenation reacted with (6-Dipp)CuBpin to generate a copper(I) borylimidinate, (6-Dipp)CuC(NR)Bpin, which went on to react with heterocumulenes. This off-cycle reactivity gives selective access to a range of novel boron-containing heterocycles bonded to copper, but precludes catalytic reactivity.
双(频哪醇合)二硼与(6-Dipp)CuOBu反应生成一种扩环的N-杂环卡宾负载的铜(I)硼基化合物，即(6-Dipp)CuBpin。该化合物表现出显著的稳定性，并通过核磁共振光谱和X射线晶体学进行了表征。(6-Dipp)CuBpin能轻易地使一系列杂累积烯，如CO、异氰酸酯和异硫氰酸酯发生脱杂原子反应，生成(6-Dipp)CuXBpin（X = O、S）。在CO的情况下，在过量双(频哪醇合)二硼存在下催化还原为CO是可行的。相比之下，在异(硫)氰酸酯的情况下，脱杂原子反应产生的异腈副产物与(6-Dipp)CuBpin反应生成一种铜(I)硼基亚氨基化合物，即(6-Dipp)CuC(NR)Bpin，该化合物继而与杂累积烯反应。这种非循环反应性使得能够选择性地获得一系列与铜键合的新型含硼杂环化合物，但排除了催化反应性。
