The heterogeneous cascade addition-oxidative cyclization of nitriles with 2-aminopyridines
or amidines was achieved in 1,2-dichlorobenzene or DMSO at 120–130 °C by using a 1,10-phenanthroline-functionalized
MCM-41-supported copper(I) complex [Phen-MCM-41-CuBr] as the catalyst and air as the
oxidant. The approach was used to generate a wide variety of 1,2,4-triazole derivatives
in mostly high yields. This heterogeneous copper(I) catalyst could be easily prepared
in a two-step procedure from commercially or readily available and inexpensive reagents
and it exhibited higher catalytic activity than the CuBr/1,10-Phen system. Phen-MCM-41-CuBr
was also easy to recover and was recyclable up to eight times with almost consistent
activity.
Key words
copper - 1,2,4-triazole - oxidative cyclization - heterogeneous catalysis - cascade
reaction
