Thiamine (VB1) modified with (3-glycidyloxypropyl)trimethoxysilane (GMSI) moiety grafted onto magnetic nanoparticles (Fe3O4@SiO2@GMSI-VB1) was prepared for the first time and applied as a magnetically retrievable catalyst for an efficient and environmental friendly synthesis of 2,3dihydroquinazolin-4(1H)-ones in aqueous media. Fe3O4@SiO2@GMSI-VB1 a have higher catalytic activity for the condensation reaction of 2-aminobenzamide and an aldehyde ketone in aqueous medium, thus providing a novel, stable and sustainable approach to the library of 3,4-dihydroquinazolin-2(1H)one derivatives. Various desired products have been prepared in good to excellent yields (72-95%) and selectivity with a wide range of substrates under identical conditions. The novel catalyst was characterized by FT-IR, XRD, SEM/EDX, TGA and VSM spectroscopy. In addition, the synthesized magnetic nanoparticles was recovered with the using a simple external magnet and was successfully reused for five runs without any appreciable loss of catalytic activity. (C) 2017 Elsevier B.V. All rights reserved.