The 12-membered cyclo-penta-[b]indole ring system in the title compound, C13H13NO2, deviates only slightly from planarity (r.m.s. deviation = 0.051 Å). In the crystal, N-H⋯O and O-H⋯O hydrogen bonds link the mol-ecules into sheets parallel to (100). The five-membered cyclopentanone ring is in slightly distorted envelope conformation with the C atom bearing the hydroxy substituent as the flap.

In the title compound, C(14)H(18)N(2)O, both the spiro-linked five-membered rings adopt envelope conformations, with a C atom as the flap in one ring and an N atom in the other. The dihedral angle between the two four-atom planes is 80.46 (8)°. In the crystal, the mol-ecules are linked by N-H⋯O hydrogen bonds to generate C(4) chains propagating in [010].

In the title compound, C(18)H(18)O(4), the six-membered chroman-4-one ring adopts an envelope conformation with the C atom bonded to the bridging CH(2) atom as the flap. The dihedral angle between the mean plane of the fused pyranone ring and the dimeth-oxy-substituted benzene ring is 89.72 (2)°. In the crystal, adjacent molecules are linked via C-H⋯π inter-actions.

In the title compound, C10H16N2O9S3, the pyrimidine ring of the 1,3-dimethyl barbituric acid moiety has an envelope conformation with the C atom carrying the methyl-sulfonyl and bis-(methyl-sulfon-yl)methyl substituents as the flap. The dihedral angle between mean plane of the pyrimidine ring and the S/C/S plane is 72.4 (3)°. In the crystal, mol-ecules are linked via C-H⋯O hydrogen bonds, formi...

In the title compound, C(17)H(19)NO(7), the cyclo-pentane ring is in an envelope conformation in which the methyl-ene group forming the flap is cis to the cyclo-propane group. The relative configuration between the 4-nitro-benzo-yloxy substituent on the side chain and the cyclo-propane ring is trans and the methoxy-lmethyl group adopts the expected conformation in which the two O atoms are gauc...

The title compound, C25H29ClO4, adopts a trans conformation about the C=C double bond and the di-methyl-cyclo-hexenone rings both show an envelope conformation with the dimethyl-substituted C atom as the flap. In the mol-ecule, the hy-droxy and carbonyl groups form two intra-molecular O-H⋯O hydrogen bonds typical for xanthene derivatives. In the crystal, weak C-H⋯O hydrogen bonds link the mol-e...

In the title compound, C28H25N3O4, the central pyrrolidine ring adopts adopts an envelope conformation with the N atom as the flap and the piperidine ring adopts a chair conformation. The pendant pyrrolidine ring is almost planar (r.m.s. deviation = 0.008 Å). An intra-molecular C-H⋯O inter-action closes an S(6) ring. In the crystal, inversion dimers linked by pairs of N-H⋯O hydrogen bonds gener...

In the title di-hydro-dioxin, C31H28O5, the dioxane ring has a chair conformation, whereas each of the pyran and dioxine rings has an envelope conformation with methyl-ene and quaternary C atoms, respectively, being the flap atoms. The phenyl rings are cis and form a dihedral angle of 82.11 (10)°. The molecular structure is stabilized by C-H⋯O contacts. In the crystal packing, supra-molecular l...

In the title compound, C(18)H(19)NO(2), the five-membered ring of the indane fragment adopts an envelope conformation, with the unsubstituted C atom, acting as the flap atom, deviating by 0.412 (3) Å from the plane through the remaining four atoms. The dihedral angle between the nitro-phenyl ring and the indane benzene ring is 72.5 (1)°. The distances from the two O atoms to the plane of the ad...

The asymmetric unit of the title compound, C10H14N2O3, contains two independent mol-ecules with similar conformations. In the both mol-ecules, the cyclo-hexene rings adopt the same envelope conformation with the flap C atoms lying 0.658 (3) and 0.668 (3) Å from the mean planes formed by the remaining atoms. In the crystal, adjacent mol-ecules are connected via N-H⋯O hydrogen bonds and weak C-H⋯...