Experimental

R factor = 0.040; wR factor = 0.116; data-to-parameter ratio = 16.3. In the title compound, C20H17N3O4, the central pyran ring adopts a boat conformation with the O atom and diagonally opposite C atoms displaced by 0.1171 (1) and 0.1791 (1) Å, respectively, from the mean plane defined by the other four atoms. The coplanar atoms of the pyran ring and the methoxybenzene ring are nearly perpendicular, as evidenced by the dihedral angle 87.01 (1). The amine H atom forms an intramolecular N—H O(nitro) hydrogen bond. In the crystal, molecules are linked into dimeric aggregates by N— H O(nitro) hydrogen bonds, generating an R22(12) graph-set motif. Related literature For background to compounds containing the 4H-pyran unit