KNOEVENAGEL, WITTIG AND WITTIG-HORNER REACTIONS IN THE PRESENCE OF MAGNESIUM OXIDE OR ZINC OXIDE.

Article abstract of DOI:10.1016/S0040-4020(01)89986-5

Alkenes are prepared by Wittig, Knoevenagel and Wittig-Horner reactions in solid-liquid systems, with magnesium oxide or zinc oxide as catalyst.When Wittig-Horner reaction is competitive with Knoevenagel reaction, the catalyst can by modified to give a highly selective reaction : the addition of dimethylsulfoxide on MgO or hexamethylphosphoric triamide on ZnO gives more efficient catalysts for the Wittig-Horner reaction.The addition of a small amount of HgCl2 or CdCl2 on ZnO gives more efficient catalysts for the Knoevenagel reaction.