In this work, the graphene oxide (GO) was formed via modified Hummer's method. Then, magnetic graphene oxide nanocomposite (GO Ni-MNC) was prepared by magnetization of GO via magnetic nickel nanoparticles (Ni-MNPs). Then, the surface of GO Ni-MNC was modified using 3-iodopropyltrimethoxysilane (3-IPTMS). Then, a new lanthanum complex of (3-pyridin-3-ylmethyl)2thiourea was anchored on the surface of modified GO Ni-MNC, which labeled as La-PMTU@GO Ni-MNC. This nanocatalyst was identified with SEM, EDS, WDX, XRD, BET and VSM techniques. La-PMTU@GO Ni-MNC were investigated as a new, high effective, returnable and homoselective nanocatalyst for the production of tetrahydrobenzo[b]pyrans and pyranopyrazoles through multicomponent reactions. The homoselectivity of this catalyst was confirmed by NMR spectroscopy. This La-PMTU@GO Ni-MNC catalyst exhibited a good reusability for up to four runs without meaningful loss of catalytic performance.
