2-(Naphthalen-1-yl)-4-(naphthalen-1-yl-methyl-idene)-1,3-oxazol-5(4H)-one.

In the title compound, C(24)H(15)NO(2), the oxazole ring is oriented at dihedral angles of 10.09 (4) and 6.04 (4)° with respect to the mean planes of the naphthalene ring systems, while the two naphthalene ring systems make a dihedral angle of 4.32 (3)°. Intra-molecular C-H⋯N hydrogen bonds link the oxazole N atom to the naphthalene ring systems. In the crystal, inter-molecular weak C-H⋯O hydrogen bonds link the mol-ecules into centrosymmetric dimers. π-π contacts between the oxazole and naphthalene rings and between the naphthalene ring systems [centroid-centroid distances = 3.5947 (9) and 3.7981 (9) Å] may further stabilize the crystal structure. Three weak C-H⋯π inter-actions also occur.

2-(Naphthalen-1-yl)-4-(thio-phen-2-yl-methyl-idene)-1,3-oxazol-5(4H)-one.

The asymmetric unit of the title compound, C(18)H(11)NO(2)S, contains two crystallographically independent mol-ecules. In one mol-ecule, the oxazole and thio-phene rings are oriented at dihedral angles of 17.40 (9) and 18.18 (7)° with respect to the naphthalene ring system, while the oxazole and thio-phene rings are oriented to each other at a dihedral angle of 0.86 (9)°. In the other mol-ecule, the corresponding angles are 3.05 (8), 9.62 (6) and 7.02 (8)°, respectively. In each mol-ecule, a weak intra-molecular C-H⋯N hydrogen bond links the oxazole N atom to the naphthalene group. Weak inter-molecular C-H⋯O hydrogen bonding is present in the crystal structure. π-π stacking between the oxazole and thio-phene rings, between the thio-phene and naphthalene rings, and between the oxaozole and naphthalene rings, [centroid-centroid distances = 3.811 (2), 3.889 (2), 3.697 (2) and 3.525 (2) Å] may further stabilize the crystal structure.

Ethyl 4-oxo-2,3,4,9-tetra-hydro-1H-carbazole-3-carboxyl-ate.

In the title compound, C(15)H(15)NO(3), the carbazole skeleton includes an eth-oxy-carbonyl group at the 3-position. In the indole ring system, the benzene and pyrrole rings are nearly coplanar, forming a dihedral angle of 0.89 (4)°. The cyclo-hexenone ring has an envelope conformation. In the crystal, inter-molecular N-H⋯O and C-H⋯O hydrogen bonds link the mol-ecules into a three dimensional network. A weak C-H⋯π inter-action is also observed.

11-Butyl-3-meth-oxy-11H-benzo[a]carbazole.

The title compound, C(21)H(21)NO, consists of a carbazole skeleton with a meth-oxy-benzene ring fused to the carbazole, and a butyl group attached to the carbazole N atom. The carbazole skeleton is nearly planar [maximum deviation = 0.078 (2) Å], and it is oriented at a dihedral angle of 4.22 (4)° with respect to the adjacent meth-oxy-benzene ring.