| abstract |
In the preparation of 1,4-dihydropyridine derivatives of formula (I), the improvement which comprises reacting a 2-haloethyl 2-benzylidene-3-oxobutanoate of formula (IV) with a 3-aminocrotonic acid ester of formula (V) in a reaction medium in the presence of a dehydrating agent.n n In the formulae R¹, R², R³ and X have the same meanings as defined in the claims. |