Ethyl 2-[4-(4-meth-oxy-benz-yl)-3-methyl-6-oxopyridazin-1-yl]acetate.

In the title mol-ecule, C 17 H 20 N 2 O 4 , the inner part of the ester substituent is nearly perpendicular to the di-hydro-pyridazine ring, forming a dihedral angle of 83.21 (7)°. In the crystal, inversion dimers are formed by pairwise C-H⋯O inter-actions with the dimers connected into chains extending along the b -axis direction by C-H⋯π(ring) inter-actions. The chains are connected by π-stacking inter-actions to give corrugated layers parallel to the ab plane. The terminal ethyl group is disordered over two two sets of sites with the major component having a site occupancy factor of 0.715 (10).