Design of novel 2-amino-pyrans via a green and facile one-pot multicomponent protocol using RuO2/Al2O3 as reusable catalyst

A facile, eco-friendly, and efficient approach for the multicomponent synthesis of 2-amino-pyran analogues (4a–j) is described that involves the reaction of substituted aldehydes, methyl cyanoacetate, and 1,3-cyclohexadione in a one-pot method using ruthenia-doped alumina (RuO2/Al2O3) as heterogeneous catalyst in a green solvent system. A simple wet-impregnation approach was used to prepare the catalyst material and was well-characterized using several analytical techniques like PXRD, TEM, SEM, SEM–EDX, and BET analysis. The key benefits of the current protocol are operational simplicity, economy, green reaction conditions, easy workup, short reaction time (10 min), higher product yields (94–98%), and no need for column chromatographic purification. The additional key advantage of this method is the recyclability and reusability of catalyst material up to eight runs through simple filtration without any significant loss of its catalytic activity.