(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

Methyl 2,2'-dimethyl-4'-[2-(methyl-sulfan-yl)eth-yl]-1,3-dioxo-2,3-dihydro-1H,4'H-spiro-[isoquinoline-4,5'-oxazole]-4'-carboxyl-ate

In the isoquinoline ring system of the title mol-ecule, C(18)H(20)N(2)O(5)S, the fused N-heterocyclic ring is distorted towards a half-boat conformation. The methyl formate moiety is disordered over two sets of sites with refined occupancies of 0.882 (5) and 0.118 (5). In the crystal, mol-ecules are linked via weak inter-molecular C-H⋯O hydrogen bonds into one-dimensional chains along [010].

Methyl 2-acetamido-2-(4-hydroxy-2-methyl-1,3-dioxo-1,2,3,4-tetrahydroisoquinolin-4-yl)-4-methylpentanoate

In the isoquinoline ring system of the title mol­ecule, C₁₉H₂₄N₂O₆, the N-heterocyclic ring is in a half-boat conformation. The mol­ecular structure is stabilized by an intra­molecular O—H⋯O hydrogen bond, which generates an S(7) ring motif. In the crystal, mol­ecules are linked via inter­molecular bifurcated N—H⋯(O,O) and weak C—H⋯O hydrogen bonds into a three-dimensional network.

Methyl 4'-benzyl-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(22)H(20)N(2)O(5), the N-heterocyclic ring is in a half-boat conformation. The least-squares plane of the dioxa-2-aza-spiro ring [maximum deviation = 0.076 (1) Å] and forms a dihedral angle of 14.54 (4)° with the phenyl ring. In the crystal, mol-ecules are linked via inter-molecular C-H⋯O hydrogen bonds into layers parallel to (100).

5-Meth-oxy-1,2',3-trimethyl-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 mol­ecule, C₁₆H₁₆N₂O₅, the N-heterocyclic ring is in a half-boat conformation. The dioxaaza­spiro ring is essentially planar [maximum deviation = 0.022 (1) Å] and forms a dihedral angle of 24.56 (4)° with the benzene ring.

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].

1-Benzyl-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 mol­ecule, C₂₂H₂₀N₂O₅, the N-heterocyclic ring is in a half-boat conformation. The dioxa-2-aza­spiro ring is essentially planar [maximum deviation = 0.026 (1) Å] and forms dihedral angles of 22.53 (5) and 64.46 (5)° with the benzene and phenyl rings, respectively. The mol­ecular structure is stabilized by a weak intra­molecular C—H⋯O hydrogen bond, which generates an S(7) ring motif. In the crystal, mol­ecules are linked via weak inter­molecular C—H⋯O and C—H⋯N hydrogen bonds into layers parallel to (102).

(1S*,4'S*,5R*)-1-Isobutyl-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 compound, C₁₉H₂₂N₂O₅, the N-heterocyclic ring is in a half-chair conformation. The dioxa-2-aza­spiro 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, mol­ecules are linked via weak inter­molecular C—H⋯O and C—H⋯N hydrogen bonds into chains along [010].