New Insight into the Reactivity of S,S-Bis-ylide.

The present work focuses on the reactivity of S,S-bis-ylide , which presents a strong nucleophilic character, as evidenced by reactions with methyl iodide and CO, affording C-methylated salts and betaine , respectively. The derivatization of betaine affords the corresponding ester derivative , which is fully characterized by using NMR spectroscopy and X-ray diffraction analysis. Furthermore, an original reaction with phosphenium ions leads to the formation of a transient push-pull phosphino(sulfonio)carbene , which rearranges to give stabilized sulfonium ylide derivative .