1. Context

Organophosphorus compounds play a vital role in organic synthesis, and are used on a daily basis in academic laboratories and on a large scale in industry. Among the reactions promoted by phosphines are those of Wittig and aza-Wittig (formation of carbon-carbon and carbon-nitrogen double bonds), Mitsunobu (nucleophilic substitution on alcohol functions), Appel (alcohol halogenation reaction) or Staudinger (azide reduction to amine or amide formation reaction)