Elgodipine can be obtained in three main steps: The alkylation of N-methyl-2-aminoethanol (I) with 4-fluorobenzyl chloride (II) gives 2-[N-(4-fluorobenzyl)-N-methylamino]ethanol (III), which is esterified with 2,2,6-trimethyl-4H-1,3-dioxin-4-one (IV) yielding the corresponding acetoacetic ester (V). The condensation of (V) with 2,3-methylenedioxybenzaldehyde (VI) affords 2-[N-(4-fluorobenzyl)-N-methylamino]ethyl 2-(2,3-methylenedioxybenzylidene]acetoacetate (VII), which is finally cyclized with isopropyl 3-aminocrotonate (VIII). The intermediate aldehyde (VI) is obtained starting from 2,3-dimethoxybenzaldehyde (X), which by demethylation with HCl or HBr yields 2,3-dihydroxybenzaldehyde (XI). Finally, this compound is converted into (VI) in the usual way. The intermediate crotonate (VIII) is obtained by reaction of isopropyl acetoacetate (IX) with ammonia.
The cyclization of 2,3-dihydroxybenzaldehyde (I) with dibromomethane by means of KF in hot DMF gives 2,3-methylenedioxybenzaldehyde (II), which is condensed with ethyl acetoacetate (III) by means of piperidine and acetic acid in refluxing benzene to afford ethyl 2-acetyl-3-(2,3-methylenedioxyphenyl)acrylate (IV). Finally, this compound is cyclized with methyl 3-aminocrotonate (V) in hot isopropanol.