Natural Phosphate Doped with Potassium Fluoride: Efficient Catalyst for the Construction of a Carbon−Carbon Bond

Abstract

Natural phosphate-doped catalyst was found to be an efficient, environmentally attractive, and selective solid base catalyst for 1,4-Michael addition. The products of undesirable side reactions resulting from 1,2-adddition, polymerization, and bis-addition are not observed. The workup procedure is simplified by simple filtration with the use of natural phosphate alone or doped with potassium fluoride. Potassium fluoride-doped natural phosphate is used as catalyst for a facile synthesis of 4H-chromene under heterogeneous conditions.