[γ-Fe2O3@HAp-SO3H] an efficient nanocatalyst for the synthesis of highly functionalised 2-thioxopyrido[2,3-d]pyrimidines

HAp(hydroxyapatite)-encapsulated-gamma-Fe2O3 supported sulfonic acid nanoparticles were used for the preparation of two series of 2-thioxopyrido[2,3-d]pyrimidines. In the first series, 2-thioxopyrido[2,3-d]pyrimidines were synthesised from 3-(6-amino-1,2,3,4-tetrahydro-4-oxo-2-thioxopyrimidin-5-yl)-3-oxopropanenitrile and arylaldehydes in the presence of [gamma-Fe2O3@HAp-SO3H] as a nanocatalyst, in high yields (84-96%). In the second series, [gamma-Fe2O3@HAp-SO3H] was used to catalyse the reaction of 6-amino-2-(alkylthio)-pyrimidine-4,6(1H,5H)-dione, 1,3-diethyl-2-thioxodihydropyrimidine-4,6(1H,5H)-dione and various arylaldehydes to prepare 2-thioxo-2,3,7,10-tetrahydropyrido[2,3-d:5,6-d'] dipyrimidine-4,6 (1H,5H)-diones in excellent yields (93-98%).