In the isoquinoline ring system of the title compound, C(19)H(22)N(2)O(5), the N-heterocyclic ring is in a half-chair conformation. The dioxa-2-aza-spiro ring is essentially planar [maximum deviation of 0.025 (1) Å] and forms a dihedral angle of 23.51 (5)° with the benzene ring. In the crystal, mol-ecules are linked via weak inter-molecular C-H⋯O and C-H⋯N hydrogen bonds into chains along [010].