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-磷杂双环烯到5-磷杂环戊烯衍生物的二-π-甲烷重排，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。它提供了一个简单的和选择性的访问手性，空间要求，刚性和构型稳定的有机磷（III）化合物。在第一个资助期（2017 - 2020年），从根本上系统地研究了光诱导形成5-磷酸半牛瓦烯衍生物。通过这些研究，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获得重要的结果，而且能够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催化的末端和内部烯烃的氢化反应中的应用的重要信息。此外，通过密度泛函理论计算，获得了有价值的信息，二-π-甲烷重排的配合物结合的1-磷杂双环烯的机制。部分结果已经发表在四个同行评审的期刊上，或者在一系列讲座中发表。目前正在编写至少另外两份出版物。此外，在金属配位圈中，1-磷杂双环烯的二-π-甲烷重排生成5-磷杂半环戊烯衍生物被认为是一个“亮点”。此外，还就该项目撰写了一篇论文。第二个资助期的重点特别是i）开发双齿/螯合5-磷酸半牛烯; ii）配位化合物中的二-π-甲烷重排; iii）获得仍然未知的2-磷酸半牛烯; iv）机理研究; v）在前手性烯烃的对映选择性加氢反应中建立（对映异构纯）5-磷酸半牛烯。重点研究了铑催化的内烯和反应活性较低的烷基烯烃对映选择性加氢生成相应的手性（内）醛。对于这一极具挑战性的反应，迄今为止文献中已知的选择性分子催化剂体系非常少。

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.