Preparation, characterization and application of nano-[Fe3O4@SiO2@R-NHMe2][H2PO4] as a novel magnetically recoverable catalyst for the synthesis of pyrimido[4,5-b]quinolines

A novel organic-inorganic hybrid magnetic nanomaterial namely nano-[Fe3O4@-SiO2@R-NHMe2][H2PO4] (nano-[FSRN][H2PO4]) has been prepared, and characterized by FT-IR, EDS, FE-SEM, VSM, XRD and TGA analyses. Afterward, an important class of uracil-bearing heterocycles namely pyrimido[4,5-b]quinolines has been synthesized through the one-pot multi-component reaction of 6-amino-1,3-dimethyluracil with arylaldehydes and dimedone using nano-[FSRN][H2PO4] as a dual-functional catalyst under solvent-free conditions. High yields, short reaction times, magnetic recoverability of the catalyst, no need to column chromatography for purification of the products and good compliance with green chemistry protocols are some advantages of the work. (C) 2020 Elsevier B.V. All rights reserved.