Immobilization of copper(II) on mesoporous MCM-41: a highly efficient and recyclable catalyst for tandem oxidative annulation of amidines and methylarenes

A new 3-(2-aminoethylamino)propyl-functionalized MCM-41-immobilized copper(II) complex [MCM-41-2N-Cu(OAc)2] was easily prepared from commercially available and inexpensive 3-(2-aminoethylamino)propyltrimethoxysilane via immobilization on MCM-41, followed by reacting with copper(II) acetate and characterized by various physico-chemical techniques. It was found that this heterogeneous copper complex is a highly efficient catalyst for the tandem oxidative annulation of amidines and methylarenes with tert-butyl hydroperoxide as oxidant towards 3,5-disubstituted 1,2,4-oxadiazoles and can be reused at least eight consecutive trials with almost consistent activity.