2) This compound can also be obtained by direct cyclization of ethyl acetoacetate (I) with 3-nitrobenzaldehyde (II) and 3-aminocrotonate (IV) in refluxing ethanol.
1) The condensation of ethyl acetoacetate (I) with 3-nitrobenzaldehyde (II) in toluene gives ethyl 2-(3-nitrobenzylidene)acetoacetate (III), which is then cyclized with methyl 3-aminocrotonate (IV) [prepared from methyl acetoacetate (V) with NH3 and p-toluenesulfonic acid]; the reaction is carried out in refluxing ethanol.