News about the diagonal relationship between phosphorus and carbon: development of 5-phosphasemibullvalene derivatives and their application as P(III)-Ligands in homogeneous catalysis

我们在2016年首次描述了1-磷杂环烯的二π-甲烷重排为5-磷酸半角瓦烯衍生物，这代表了元素周期表中元素磷和碳之间一种新的有趣的对角关系。它提供了一种容易和选择性地获得手性、空间要求高、刚性和构型稳定的有机磷(III)化合物的途径。在第一个资助期(2017-2020年)，我们从根本上和系统地研究了5-磷酸半角豆烯衍生物的光诱导形成。通过这样做，我们不仅能够在这些磷化合物的合成、配位化学和对映体的分离方面取得重要的结果，而且还可以获得关于它们的立体电子性质以及它们作为配体在Au(I)催化的环化反应和Rh催化的端烯和内烯的氢甲酰化反应中的重要信息。此外，通过密度泛函理论计算，得到了关于络合物结合的1-磷杂环己烯的二π-甲烷重排反应机理的有价值的信息。部分研究结果已经在四个同行评议的期刊上发表，或在一系列讲座中发表。至少还有两份出版物正在筹备中。此外，在金属配位体系中，1-磷杂环烯的二π-甲烷重排反应被认为是一个“亮点”。此外，还撰写了关于该项目的论文。第二个供资期的重点尤其是：i)双齿/螯合5-磷酸半牛角烯的开发；ii)二π-甲烷在配位化合物中的重排；iii)获得未知的2-磷酸半牛角烯；iv)机理研究；v)在前手性烯烃的对映选择性氢甲酰化反应中建立(对映体纯化的)5-磷酸半牛瓦烯。重点放在对映选择性Rh催化的内部和活性较低的烷基-烯烃的氢甲酰化反应中，生成相应的手性(内部)醛。对于这种极具挑战性的反应，到目前为止，文献中只有很少的选择性分子催化体系。

The di-π-methane rearrangement of 1-phosphabarrelenes to 5-phosphasemibullvalene derivatives, which we first described by us in 2016, represents a new and interesting diagonal relationship between the elements phosphorus and carbon in the periodic table of the elements. It provides an easy and selective access to chiral, sterically demanding, rigid and configurationally stable organophosphorus(III) compounds. In the first funding period (2017-2020), the photoinduced formation of 5-phosphasemibullvalene derivatives was investigated fundamentally and systematically. In doing so, we were not only able to obtain important results regarding the synthesis, coordination chemistry and separation of enantiomers of these phosphorus compounds, but also important information about their stereoelectronic properties as well as their use as ligands in Au(I)-catalysed cyclization reactions and in the Rh-catalyzed hydroformylation of terminal and internal alkenes could be gained. Furthermore, valuable information on the mechanism of di-π-methane rearrangement of complex-bound 1-phosphabarrelenes was obtained by means of DFT calculations. Parts of the results have already been published in four peer-reviewed journals or presented in a series of lectures. At least two further publications are in preparation. Also, the di-π-methane rearrangement of 1-phosphabarrelenes to 5-phosphasemibullvalene derivatives in the coordination sphere of metals was acknowledged as a "highlight". Furthermore, a dissertation was written on this project. The focus of the second funding period is in particular i) the development of bidentate/chelating 5-phosphasemibullvalene; ii) di-π-methane rearrangement in coordination compounds; iii) access to still unknown 2-phosphasemibullvalenes; iv) mechanistic investigations; v) the establishment of (enantionmerically pure) 5-phosphasemibullvalenes in the enantioselective hydroformylation of prochiral alkenes. The focus is on the enantioselective Rh-catalyzed hydroformylation of internal and less reactive alkyl-alkenes to the corresponding chiral (internal) aldehydes. For this extremely challenging reaction, there are so far only very few selective molecular catalyst systems known in the literature.