1,4-Dihydropyridine from the condensation of aldehyde, β-ketoester and ammonia. Hantzsch 1,4-dihydropyridines are popular reducing reagents in organo-catalysis. Well-known calcium channel blockers (CCBs) nifedipine (Adalat), felodipine (Plendil), and amlodipine (Norvasc) for treating hypertension all have 1,4-dihydropyridine core structures.