Schlosser modification of Wittig

Schlosser modification of Wittig reaction The presence of soluble metal salts such as lithium salts decreases the aVfrans-selectivity. The normal Wittig reaction of non-stabilized ylides with aldehydes gives Z-alkenes. The Schlosser modification of the Wittig reaction of non-stabilized ylides furnishes -alkenes. In the presence of lithium halides oxaphosphetanes can often be observed, but betaine-lithium halide adducts are also formed. If lithium salts are added to the equilibrium, oxaphosphetane formation and elimination of... 

---