The reaction of 5-hydroxy-2-nitrobenzaldehyde with ethyl acetoacetate in ammonia gave the two expected isomeric 1,4- and 1,2-dihydropyridines resulting from the normal Hantzsch reaction. However, the combination of 2-nitrobenzaldehyde with ethyl acetoacetate under the same conditions yielded four products: the two normal isomeric dihydropyridines and two tricyclic compounds. When we attempted to independently