1,4-Dihydro­benzo[g]quinoxaline-2,3-dione

The title compound, C₁₂H₈N₂O₂, was prepared by the reaction of the diethyl ester of naphthalene­bis­(oxamate) with tert-BuNH₂. The mol­ecule is nearly planar, with an r.m.s. deviation of 0.017 Å from the plane through all 16 non-H atoms. In the crystal, a three-dimensional network is formed, composed of layers of mol­ecules along the b- and c-axis directions, due to the formation of inter­molecular N—H...O hydrogen bonds, as well as of chains along the a-axis direction due to parallel displaced sandwich-type π–π inter­actions with average distances between the inter­acting mol­ecules in the range 3.35–3.40 Å.