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

在我们的初步工作中，我们可以证明，利用强刘易斯酸性硼烷与五氟苯基取代基极大地提高了1,1-碳硼化反应的速率和范围。在这种情况下，氢的迁移能力足以将简单的末端炔转化为它们各自取代的烯基硼烷。P-、S-和b -在这些条件下发生迁移，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。我们想用这种方法来准备扩展的pi系统。随后的氧化酰化将导致共轭烯酮。应从邻近的二乙炔开始制备环状变体。我们提出了不饱和邻二乙炔的环化，以得到苯环化产品。该项目的一个重点将是发展噻吩、磷孔和硼孔的化学性质，它们将从各自容易制备的双乙酰基取代杂原子前体开始，通过1,1-碳硼化序列方便地获得。最终，我们计划通过1,1-碳硼化方案开发对称和不对称含S， P和b的环五元pi-体系的简单合成，这可能会对有机材料科学产生潜在的兴趣。

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.