By cyclization of methyl 2,3-dichlorobenzyldeneacetoacetate (I) with ethyl 3-aminocrotonate (II) in tert-butanol at room temperature.
By cyclization of 2,3-dichlorobenzaldehyde (I) with 3-aminocrotonic acid ethyl ester (II) and acetylacetic acid methyl ester (III) in refluxing ethanol.
By cyclization of 2-(2,3-dichlorobenzylidene)acetyl acetic acid methyl ester (IV) with acetylacetic acid ethyl ester (V) and ammonia (VI) in tert-butanol.