Dihydropyrimidine calcium channel blockers. II. 3-Substituted-4-aryl-1,4-dihydro-6-methyl-5-pyrimidinecarboxylic acid esters as potent mimics of dihydropyridines
作者:Karnail S. Atwal、George C. Rovnyak、S. David Kimball、David M. Floyd、Suzanne Moreland、Brian N. Swanson、Jack Z. Gougoutas、Joseph Schwartz、Kaye M. Smillie、Mary F. Malley
DOI:10.1021/jm00171a044
日期:1990.9
To enhance the intrinsic potency of dihydropyrimidine calcium channel blockers, we have modified the structure of previously described 2-heteroalkyl-1,4-dihydropyrimidines 2 to 3-substituted 1,4-dihydropyrimidines 3. Structure-activity studies using potassium-depolarized rabbit aorta show that ortho, meta-disubstituted aryl derivatives are more potent than either ortho- or meta-monosubstituted compounds. While vasorelaxant activity was critically dependent on the size of the C5 ester group, isopropyl ester being the best, a variety of substituents (carbamate, acyl, sulfonyl, alkyl) were tolerated at N3. Our results show dihydropyrimidines 3 are significantly more potent than corresponding 2-heteroalkyl-1,4-dihydropyrimidines 2 and only slightly less potent than similarly substituted 2-heteroalkyl-1,4-dihydropyridines 4 and 5. Whereas dihydropyridine enantiomers usually show 10-15-fold difference in activity, the enantiomers of dihydropyrimidine 3j show more than a 1000-fold difference in activity. These results strengthen the requirement of an enamino ester for binding to the dihydropyridine receptor and indicate a nonspecific role for the N3-substituent.