Methylenetriphenylphosphorane

synthetischeMethylenetriphenylphosphine is usually prepared by treatment of a suspension of Methyltriphenylphosphonium Bromide (or iodide) in an appropriate solvent with a strong base. Butyllithium, dimsylsodium, t-BuOK, and sodamide are commonly used. Typically, a suspension of dry methyltriphenylphosphonium bromide in dry ether or THF is treated with n-Butyllithium at 0°C under N2 and the resulting solution is stirred at rt for 1 h. A yellow to deep orange color indicates the ylide formation. The dimsylsodium (Sodium Methylsulfinylmethylide) procedure requires heating a suspension of NaH in dry DMSO at 75-80 °C for 1 h followed by ice-cooling prior to the addition of phosphonium bromide. A salt-free ylide is usually prepared using Sodium Amide in liquid ammonia or in refluxing THF.