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Heidar Darmandeh, Thorsten Scherpf, Kai-Stephan Feichtner, Christopher M. Schwarz, Viktoria H. Däschlein-Gessner

• The preparation and isolation of the metalated ylides \([Cy_{3}PCSO_{2}Tol]M\) \((\bf {^{Cy}1-M)}\) (with M = Li, Na, K) are reported. In contrast to its triphenylphosphonium analogue the synthesis of \((\bf {^{Cy}1-M)}\) revealed to be less straight forward. Synthetic routes to the phosphonium salt precursor \((\bf {^{Cy}1-H_{2)}}\) via different methods revealed to be unsuccessful or low-yielding. However, nucleophilic attack of the ylide Cy3P = CH2 at toluenesulfonyl fluoride under basic conditions proved to be a high-yielding method directly leading to the ylide \((\bf {^{Cy}1-H)}\). Metalation to the yldiides was finally achieved with strong bases such as \(\it {n}\)BuLi, NaNH\(_2\), or BnK. In the solid state, the lithium compound forms a tetrameric structure consisting of a (C–S–O–Li)\(_4\) macrocycle, which incorporates an additional molecule of lithium iodide. The potassium compound forms a C\(_4\)-symmetric structure with a (K\(_4\)O\(_4\))\(_2\) octahedral prism as central structural motif. Upon deprotonation the P–C–S linkage undergoes a remarkable contraction typical for metalated ylides.