Catalytic application of sulfonic acid-functionalized titana-coated magnetic nanoparticles for the preparation of 1,8-dioxodecahydroacridines and 2,4,6-triarylpyridines via anomeric-based oxidation

We have developed green, efficient and powerful protocols for the preparation of 2,4,6-triarylpyridines and 1,8-dioxodecahydroacridines in the presence of Fe3O4@TiO2@O2PO2(CH2)(2)NHSO3H as a sulfonic acid-functionalized titana-coated magnetic nanoparticle catalyst under mild and solvent-free reaction conditions. These protocols furnished the desired products in short reaction times with good to high yields (20-40min and 80-86% in the case of 2,4,6-triarylpyridines; 15-90min and 80-93% in the case of 1,8-dioxodecahydroacridines). The final step of the mechanistic route in the synthesis of 2,4,6-triarylpyridines proceeds via an anomeric-based oxidation. Also, the nanomagnetic core-shell catalyst can be recycled and reused in both cases of the scrutinized one-pot multicomponent reactions with high turnover number and turnover frequency.