Triphenylphosphine in Wittig reaction

A general route to )8-alkylidene-butyrolactones, which are easily converted into the corresponding jS-alkylbutenolides and thence into 3-substituted furans, employs the phosphorane (64), synthesized from maleic anhydride and triphenylphosphine, in Wittig reactions with aldehydes followed by reduction of the ester group with sodium diethylaluminium hydride (Scheme 20). 

Wittig and Horner-Wittig Reactions. (Me2N)3P may be used in place of Triphenylphosphine in Wittig reactions with aldehydes and ketones (eq 6). It is advantageous because the water solubility of the byproduct, hexamethylphosphoric triamide, renders it readily removable. This method has been used for the preparation of unsaturated esters as well as alkenes (eq 7). 

---