(1S*,4'S*,5R*)-1-Isopropyl-5-meth-oxy-2',3-dimethyl-4,6-dioxa-2-aza-spiro-[bicyclo-[3.2.0]hept-2-ene-7,4'-isoquinoline]-1',3'(2'H,4'H)-dione.

In the isoquinoline ring system of the title mol-ecule, C(18)H(20)N(2)O(5), the N-heterocyclic ring is in a half-boat conformation. The dioxa-2-aza-spiro ring is essentially planar, with a maximum deviation of 0.029 (1) Å, and makes a dihedral angle of 30.63 (5)° with the benzene ring. The mol-ecular structure is stabilized by a weak intra-molecular C-H⋯O hydrogen bond, which generates a S(6) ring motif. In the crystal, mol-ecules are linked via weak inter-molecular C-H⋯O hydrogen bonds into a three-dimensional supra-molecular network. Additional stabilization is provided by π-π stacking inter-actions between symmetry-related benzene rings with a centroid-centroid distance of 3.6507 (5) Å.