Methyl 4'-isobutyl-2,2'-dimethyl-1,3-dioxo-2,3-dihydro-1H,4'H-spiro-[iso-quinoline-4,5'-oxazole]-4'-carboxyl-ate.

In the isoquinoline ring system of the title mol-ecule, C(19)H(22)N(2)O(5), the N-heterocyclic ring is in a half-boat conformation. The dioxa-2-aza-spiro ring is essentially planar [maximum deviation = 0.042 (1) Å] and forms a dihedral angle of 81.85 (4)° with the benzene ring. In the crystal, the mol-ecules are linked via inter-molecular C-H⋯O hydrogen bonds into chains along [010].