Tris(o-tolyl)[(2-(trimethylsilyl)ethylidene]phosphorane

Abstract

[104697-92-9] C26H33PSi (MW 404.65) InChI = 1S/C26H33PSi/c1-21-13-7-10-16-24(21)27(19-20-28(4,5)6,25-17-11-8-14-22(25)2)26-18-12-9-15-23(26)3/h7-19H,20H2,1-6H3 InChIKey = DAOBXPSHUHMMAU-UHFFFAOYSA-N (cis-selective Wittig reaction for synthesis of allylsilanes;1 with modification of substituents on phosphorus and silicon atoms, β-silylphosphorus ylides give allylic alcohols diastereoselectively2) Preparative Methods: prepared in situ from tris(o-tolyl)[2-(trimethylsilyl)ethyl]phosphonium iodide and n-Butyllithium in THF.1 Tris(o-tolyl)phosphorus methylide (prepared in situ from methyltris(o-tolyl)phosphonium bromide and n-BuLi in THF) and (Iodomethyl)trimethylsilane were heated under reflux in THF for 5 h. The mixture was poured into H2O and the phosphonium salt was extracted with CH2Cl2. Evaporation of the organic solvent gave an oily residue which was crystallized from THF–Et2O (mp 111–113 °C). To a stirred suspension of the phosphonium salt in THF (6 mL g−1) was added 1 equiv of n-BuLi under a nitrogen atmosphere at 0 °C and the mixture was stirred for 30 min at rt, resulting in a clear yellow ylide solution. Handling, Storage, and Precautions: unstable to air and moisture. Should be handled under a dry nitrogen atmosphere.