Design, Preparation, and Identification of Trimetallic CoNiFe ₂ O ₄ @C Yolk‐Shell Mesoporous Nanocomposite as a Nanocatalyst in the Synthesis of Naphthopyranopyrimidines

ABSTRACT The aim of this study is the preparation of the CoNiFe 2 O 4 @C nanocomposite as a catalyst for the synthesis of naphthopyranopyrimidine derivatives. The CoNiFe 2 O 4 @C nanocatalyst is a novel nanostructure with magnetic properties and a yolk‐shell architecture, which enhances the contact surface with the reactants and improves the reaction efficiency. In this research, a nanocatalyst with yolks enclosed within one or several onion‐like shells was prepared through a three‐step procedure, forming well‐defined layered structures. In the first stage, trimetallic CoNiFe 2 O 4 was prepared, and then covered by SiO 2 to form CoNiFe 2 O 4 @SiO 2 . Finally, the CoNiFe 2 O 4 @C yolk‐shell nanocomposite was prepared by removing the SiO 2 . Characterization of this nanocomposite has been performed using FT‐IR, XRD, BET, FE‐SEM, TEM, EDS, mapping, and VSM techniques. The nanocatalyst was successfully prepared, and its performance in the synthesis of several pyrimidine derivatives was evaluated for the first time. In this protocol, we report the synthesis of naphthopyranopyrimidines through a three‐component reaction involving 2‐naphthol, aldehyde, and barbituric acid using CoNiFe 2 O 4 @C as an acidic catalyst at 100°C. The products were separated using a straightforward procedure and were of high purity.