1-(2-(2,2,2-trifluoroethoxy)ethyl-1H-pyrazolo[4,3-d]pyrimidines As Potent Phosphodiesterase 5 (PDE5) Inhibitors

1H-Pyrazolo[4,3-d]pyrimidines were previously disclosed as a potent second generation class of phosphodiesterase 5 (PDE5) inhibitors. This work explores the advancement of more selective and potent PDE5 inhibitors resulting from the substitution of 2-(2,2,2-trifluoroethoxy)ethyl at the 1 position in the so-called alkoxy pocket.