Iron‐doped multi‐walled carbon nanotubes (Fe/MWCNTs) is an efficient, ecofriendly and reusable heterogeneous nanocatalyst for the one‐pot synthesis of heterocyclic compounds including bis‐spiro piperidines, piperidines, dihydro‐2‐oxopyrroles, pyrazoles and diazepines at room temperature with good to excellent yields. The heterogeneous nanocatalyst was fully characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), inductively coupled plasma (ICP) and FT‐IR analysis. Also, the structures of all prepared compounds were characterized by 1H NMR, 13C NMR, FT‐IR, mass spectrometry (MS) and elemental analysis. The major advantages of these protocols are mild and green reaction conditions, short reaction times, clean reaction, operational simplicity, easy purification and good to excellent yields with the reusable heterogeneous nanocatalyst. The catalyst was ten recycled without significant loss of activity.

Iron‐doped acidic multi‐walled carbon nanotubes (Fe@acidic‐MWCNs) were synthesized using the chemical vapor deposition (CVD) process in the presence of acetylene and ferrocene as the sources of carbon and iron nanoparticles, respectively. The Fe@acidic‐MWCNs was fully characterized by inductively coupled plasma (ICP), X‐ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman, and FT‐IR analysis. In continuation, the synergetic effect of iron nanoparticles and acidic groups of the Fe@acidic‐MWCNs was studied through the synthesis of substituted five‐membered heterocyclic compounds including 2‐substituted benzimidazoles, 2‐substituted benzothiazoles, 2‐substituted benzoxazoles, and 1‐substituted tetrazoles. Moreover, the 2‐substituted benzimidazoles were investigated by two different methods. In general, Fe@acidic‐MWCNs catalyst showed good to excellent catalytic activity. Finally, the Fe@acidic‐MWCNs catalyst displayed a high reusability and stability in the synthesis of 3 a, 5 a, 7 a, 9 a, and 11 a.

Pd-catalyzed synthesis of urea derivatives from aryl iodides and different aliphatic and aromatic amines using sodium azide and chromium hexacarbonyl is described. In this process, carbonylation of aryl iodides, Curtius rearrangement of [a]

An efficient strategy for the synthesis of benzamides from acetamides and aryl iodides using 1 mol% Pd (OAc) 2 as catalyst and Cr (CO) 6 as CO-precursor is described. This new synthetic methodology displays high functional group tolerance on both substrates and avoids the need for ligands, reducing agents, or other additives. The corresponding products were obtained in good to excellent yields at atmospheric pressure under mild reaction conditions.