Novel Potassium Channel Opener Prodrugs with a Slow Onset and Prolonged Duration of Action

(-)-(3S, 4R, 1'R, 6'S)-4-(4-Benzyl-5-oxo-3, 4-diazabicyclo[4.1.0]hept-2-en-2-yloxy)-3, 4-dihydro-3-hydroxy-2, 2-dimethyl-2H-1-benzopyran-6-carbonitrile and its derivatives with a modified benzyl group were synthesized with the objective of discovering novel ATP-sensitive potassium channel openers (PCOs) with a slow onset of action and a reduced tendency to induce tachycardia. Among the compounds synthesized, 4-(2-chlorobenzyl) derivative 5bB had potent hypotensive activity in spontaneously hypertensive rats (SHRs). In addition, compound 5bB showed the desired pharmacological profile with a slow onset and long duration of action and induction of only mild tachycardia. Compound 5bB was found to be quantitatively metabolized in rats to give active des-2-chlorobenzyl derivative 6B. These results suggest that the incorporation of an N-benzyl group is a useful method for the preparation of prodruge, the function of which is to delay the onset and prolong the duration of action of the active substance.