1,1-Carboboration of Alkynes - Development of an Unusual Reaction

在我们的初步工作中，我们可以表明，使用具有五氟苯基取代的强Lewis酸性硼烷极大地提高了1，1-碳硼化反应的速度和范围。在这种情况下，即使氢的迁移能力也足以将简单的末端炔烃转化为它们各自取代的烯基硼烷。在此条件下，P-、S-和B-发生迁移，甚至可以通过C-C键活化进行内炔的1，1-碳硼化反应。这些结果现在将用于实现1，1碳硼化反应方案的实质性扩展。我们想以这种方式准备扩展的圆周率系统。随后的氧化脱氧反应将导致共轭烯酮的生成。环状变体应从邻二乙炔开始制备。我们建议不饱和邻二乙炔进行环化反应，得到苯环化产物。该项目的一个重点将是开发噻吩类、磷烯类和硼烯类化合物的化学，这些化合物应该可以通过1，1-碳硼化反应序列方便地获得，这些化合物都是从各自易于制备的含有双乙酰基取代的杂原子前体开始的。最终，我们计划通过1，1-碳硼化反应发展成对称和不对称的含S、P和B的环状五元pi体系，这可能会在有机材料科学中引起人们的兴趣。

In our preliminary work we could show that the utilization of strongly Lewis-acidic boranes with pentafluorophenyl substituents enormously enhanced the rates and scope of the 1,1-carboboration reaction. In this situation even die migrating aptitude of hydrogen is sufficient to convert simple terminal alkynes into their respective substituted alkenyl boranes. P-, S- and B-migration takes place under these conditions and one can even carry out 1,1-carboboration reactions of internal alkynes by means of C-C bond activation. These results shall now be used to achieve a substantial expansion of the 1,1 carboboration reaction scheme. We want to prepare extended pi-systems in this way. Subsequent oxidative deborylation will then lead to conjugated enones. Cyclic variants shall be prepared starting from vicinal diacetylenes. We propose the cyclization of unsaturated vicinal diacetylenes to give benzannulated products. One focus of the project will be the development of the chemistry of thiophenes, phospholes and boroles which should become available conveniently by 1,1-carboboration sequences starting from the respective readily prepared doubly acetylide substituted heteroatom containing precursors. Eventually, we have planned to develop simple syntheses to symmetrical and unsymmetrical S-, P- and B-containing cyclic five-membered pi-systems by the 1,1-carboboration scheme, which might potentially be of interest in organic materials science.