One‐pot synthesis of dihydro-1H-indeno[1,2-b] pyridines and tetrahydrobenzo[b] pyran derivatives using a new and efficient nanocomposite catalyst based on N‐butylsulfonate‐functionalized MMWCNTs-D-NH2

Abstract

In this study, magnetic multi-walled carbon nanotubes were functionalized with polyamidoamine (PAMAM) dendrimers and modified with butylsulfonate to afford MMWCNTs-D-(CH2)4-SO3H. The synthesized nanocomposite (MMWCNTs-D-(CH2)4-SO3H) was characterized by various techniques such as Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermo-gravimetric analysis (TGA). This nanocomposite catalyst effectively catalyzed four and three component reactions for the synthesis of dihydro-1H-Indeno[1,2-b] pyridines and tetrahydrobenzo[b] pyrans (85–98% yield in 15–20 min and 80–98% yield in 12–30 min, respectively). In addition, the magnetically recoverable catalyst could be easily recycled at least five times without significant loss of catalytic activity. In the first step of synthesis of nanocomposite the Fe3O4 nanoparticles were deposited on oxidized MWCNTs, then a modified PAMAM dendrimer was used to bond to the carbonyl groups. Finally MMWCNTs-D-NH2 functionalized with 1,4‐butanesultone.