Chemistry Department, Macalester College, Saint Paul, MN, 55105, USA.
Department of Chemistry, University of Minnesota, Minneapolis, MN, 55455, USA.
Chemistry. 2019 Dec 2;25(67):15257-15261. doi: 10.1002/chem.201904131. Epub 2019 Oct 25.
This work describes the unexpected formation of an unusual phosphonium ylide when attempting the synthesis of bisphosphonium pyromellitic diimides. Spectroscopic and crystallographic characterization reveals that a combination of π-π and CH⋅⋅⋅O interactions leads to supramolecular homodimerization of the ylide both in solution and in the solid-state. Only strong acids are able to protonate the ylide, which is otherwise inert to Wittig and alkylation reactivity. Taken together, these observations indicate that this compound is one of the most highly stabilized phosphonium ylides discovered to date.
这项工作描述了在尝试合成双膦盐均苯四酸二酰亚胺时， unexpectedly 形成了一种不寻常的磷叶立德。光谱和晶体学表征表明，π-π 和 CH⋅⋅⋅O 相互作用的结合导致叶立德在溶液和固态中均发生超分子同型二聚化。只有强酸才能质子化叶立德，否则叶立德对 Wittig 和烷基化反应无活性。综上所述，这些观察结果表明，该化合物是迄今为止发现的最稳定的磷叶立德之一。
