Mixed crystalline phases and catalytic performance of OMS-2 based nanocomposites for one-pot synthesis of quinazolines with O2 as an oxidant

In this work, a series of sodium phosphotungstate modified manganese oxide octahedral molecular sieve (OMS-2) catalysts ([PW]-OMS-2) were developed, and their catalytic activities were investigated by one-pot synthesis of quinazolines from benzyl alcohol and 2-aminobenzylamine with O-2 as green oxidant in dimethyl carbonate (DMC). TEM, XRD and EDS confirmed that sodium phosphotungstate decomposed into phosphotungstic acid and sodium tungstate in the doping process. Meanwhile, phosphotungstic acid attached and located at the surface of OMS-2 and W ions were successfully doped into the OMS-2 framework. For comparison, phosphotungstic acid/ OMS-2 was prepared by simple wet impregnation method. The [PW]-OMS-2 is the most highly selective and effective over than phosphotungstic acid/OMS-2 and OMS-2 itself in the one-pot synthesis of quinazolines. It may be due to the synergetic effect of phosphotungstic acid and OMS-2, and successfully doping W into OMS-2 frameworks. Hence, this work provides a new environmentally-friendly and heterogeneous OMS-2 based nanocomposites and it may be put into practice to synthesize heterocyclic compounds.