Advances in the greener synthesis of chromopyrimidine derivatives by a multicomponent tandem oxidation process

A hydrophilic cobalt/copper heterogeneous bimetallic catalyst named mTEG-CS-Co/Cu-Schiff-base/IL was successfully synthesized from chitosan polysaccharide. The new catalyst was investigated and confirmed using various techniques including FT-IR, FE-SEM, EDX-EDS, XRD, TEM, TGA, AFM, NMR and ICP. The catalyst exhibited powerful catalyst activity for the tandem one pot oxidative chromopyrimidine reaction from benzyl alcohols under mild conditions, utilizing air as a clean source in a green protocol. The catalyst was compatible with a wide range of benzyl alcohols, and aldehydes formed in situ, and bis-aldehydes synthesized were condensed with urea/4‑hydroxycumarin to provide favorable products in good yields for all derivatives (14 new derivatives). The presence of tri-ethylene glycol and imidazolium moieties with hydrophilic properties on the mTEG-CS-Co/Cu-Schiff-base/IL nanohybrid provides dispersion of the nanohybrid particles in water, leading to higher catalytic performance. Furthermore, the reaction exhibited several other notable features, including low catalyst loading, the ability to be recycled for up to 6 stages, high atom economy, a simple work procedure, short reaction time, utilization of an environmentally friendly nanohybrid, and the replacement of volatile and organic solvents with water solvent.