The syntheses and in vitro evaluation of a new series of pyrido[2,3-d]pyrim
idine-2,4-diones bearing substituents at C-3 and/or C-4 positions on the py
ridine ring are described. Some of these compounds, especially 51 and 6f, w
ere found to be potent phosphodiesterase 4 (PDE 4) inhibitors exhibiting im
proved ratio of PDE 4 inhibitory activity:rolipram binding assay (RBA). (C)
2001 Elsevier Science Ltd. All rights reserved.