Synthesis and biological activity of pyrido[3’,2’:4,5]furo[3,2-d]pyrimidine derivatives as novel and potent phosphodiesterase type 4 inhibitors

Abstract A series of pyrido[3′,2′:4,5]furo[3,2-d]pyrimidines (PFP) were synthesized and tested for phosphodiesterase type 4 (PDE4) inhibitory activity, with the potential to treat asthma and chronic obstructive pulmonary disease (COPD). Structure–activity relationships within this series, leading to an increase of potency on the enzyme, is presented. Both gem -dimethylcyclohexyl moieties fused to the pyridine ring and the substitution at the 5 position of the PFP scaffold, proved to be key elements in order to get a high affinity in the enzyme.