An efficient and recyclable 3D printed α-Al2O3 catalyst for the multicomponent assembly of bioactive heterocycles

A catalytic methodology is reported that enables the efficient, operationally simple and environmentally friendly synthesis of diverse 1,4-dihydropyridines and 3,4-dihydropyrimidin-2(1H)-ones, including some relevant drugs and pharmacologically active derivatives. This strategy is based on the use of a 3D printed Al2O3 woodpile material that was sintered to generate a rigid structure with controlled porosity and noteworthy catalytic performance. The 3D printed Al2O3 catalyst exhibits remarkable efficacy as a Lewis acid in Biginelli and Hantzsch reactions and it can be recovered and reused ten times without any decrease in the activity. Remarkable E factors, excellent recyclability and scalability, broad substrate scope, short reaction times, excellent yields, solvent-free conditions and easy isolation procedures are key features of this methodology. (C) 2016 Elsevier B.V. All rights reserved.