The title compound crystallizes with a disordered nitro group in twinned crystals. In the crystal, the N—H group donates a hydrogen bond to a nitro oxygen atom, generating chains propagating in the [101] direction. The amide carbonyl oxygen atom is not involved in the hydrogen bonding.

The title compound was synthesized from a di­nitro­biphenyl­benzene derivative using a novel modification of the Cadogan reaction. The reaction has several possible ring-closed products and the title compound was separated as the major product. It crystallizes in the monoclinic P space group and possesses a single closed Cadogan ring.

Two compounds arose from the same reaction in methanol and the other arose from an unexpected reaction with the acetone solvent.

The title compound is more planar than its 3-nitro isomer in the solid state and differs in its hydrogen-bonding pattern.

A series of three 1,1,4-triphenyl-substituted 1,3-enynes have been structurally characterized by X-ray diffraction at 100 K. Biological tests for one enyne revealed that it inhibited the growth of Aspergillus niger. Such 1,3-enynes find widespread applications in organic synthesis and biological tests.

In the title compound, the nitro groups are rotated significantly out of the plane of the benzene ring and the amine group forms a bifurcated N—H(O,O) hydrogen bond with intra­molecular and inter­molecular components.

In the title compound, C₁₅H₁₁N₃O₄, the oxazine ring exhibits a half chair conformation, and the pyrrolidine ring adopts an envelope conformation; the dihedral angle between them is 78.63 (9)°. In the crystal, mol­ecules are linked via N—HO and C—HO hydrogen bonds into sheets parallel to the bc plane.

X-ray crystallography revealed the unintended formation of benziso­thia­zolinone 1-oxides from 1,3-benzo­thia­zin-4-ones through oxidation instead of the anti­cipated benzo­thia­zinone sulfones, which would be constitutional isomers.

The title mol­ecules were synthesized by the reaction of the corresponding sodium benzoate with chloro­acetic acid amide. Single crystals were obtained from the reaction products under the same conditions.

The treatment of non-fully substituted 4,4-di­fluoro-4-bora-3a,4a-di­aza-s-indacene (BODIPY) with cupric nitrate leads to the introduction of a nitro group at different positions of the BODIPY core, depending on the substitution pattern. This methodology complements the treatment of fully substituted BODIPY with cupric nitrate that was previously reported. In all three structures, the fused ring system is in a very flattened `V-shape' and the central six-membered ring adopts a flattened sofa conformation.