Nanoparticles tungstophosphoric acid supported on polyamic acid: catalytic synthesis of 1,8-dioxo-decahydroacridines and bulky bis(1,8-dioxo-decahydroacridine)s

Tungstophosphoric acid nanoparticles supported on polyamic acid (TPA NPs/PAA) was prepared and employed as a catalyst for the facile selective synthesis of 1,8-dioxo-decahydroacridines and some bulky bis(1,8-dioxo-decahydroacridine)s via one-pot condensation of 5,5-dimethyl-1,3-cyclohexanedione and various aldehydes with aniline or ammonium acetate in ethanol–water solution. This catalyst was characterized by FT-IR, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TG), energy-dispersive X-ray analysis (EDAX), and inductively coupled plasma optical emission spectrometry (ICP-OES). The catalyst showed high thermal stability and good reusability. The products were isolated in high purity and the catalyst was easily separated in a simple workup and recycled several times without noticeable loss of activity under the described reaction conditions. The reaction is characterized by short reaction time, high efficiency, and mild reaction conditions.