Manganese oxide nanoparticles (Mn3O₄-NPs) were used as a heterogeneous nano catalyst in this work to create a novel series of pyrimidine derivatives in an ecologically acceptable manner. Simple and easily accessible starting ingredients were used in a one-pot, multicomponent reaction as part of the synthetic approach. Co-precipitation was used to create the Mn3O₄-NPs, and XRD and SEM were used to verify their crystalline structure and nanoscale shape. FT-IR, UV-visible, ¹H NMR, and elemental CHN analysis were among the spectroscopic methods used to establish the structural identity of the synthesized pyrimidine derivatives. The MTT test was used to assess the newly synthesized compounds' anticancer potential in vitro against human cancer cell lines. The compounds' selectivity was also evaluated by measuring their cytotoxicity to normal cells. Several derivatives of the investigated drugs showed …