Synthesis and antihypertensive activity of 4-(diazabicyclo[4.1.0]-heptenyloxy)benzopyran derivatives and their analogues

A series of 3,4-dihydro-3-hydroxy-4-(5-oxo-3,4-diazabicyclo4.1.0]hept- 2-en-2-yl)oxy]-2H-1-benzopyrans and their analogues were synthesized and evaluated on potassium channel opening and hypotensive activities. Compound (-)-13B with a (4-methyl-5-oxo-3,4-diazabicyclo4.1.0]hept-2-en-2-yl)oxy group for the 4-position of the benzopyran ring was 3 times as potent as EMD 57283 (II), the lead compound, in hypotensive activity. The results would demonstrate that 5-oxo-3,4-diazabicyclo4.1.0]hept-2-en-2-yloxy moieties are effective as the substituents at the 4-position of benzopyran-type potassium channel openers.