Ethyl 4-hydroxy-9-tosyl-9H-carbazole-3-carboxylate

In the title compound, C₂₂H₁₉NO₅S, the carbazole skeleton is nearly planar [maximum deviation = 0.043 (1) Å] with the pyrrole ring oriented at dihedral angles of 2.32 (6) and 1.77 (6)° with respect to the adjacent benzene rings. The dihedral angle between the benzene ring of the tosyl group and the carbazole skeleton is 82.25 (5)°. Intra-molecular O - H⋯O hydrogen bonding results in the formation of a planar six-membered ring, which is oriented at a dihedral angle of 3.06 (4)° with respect to the adjacent carbazole skeleton. In the crystal structure, weak inter-molecular C - H⋯O inter-actions link the mol-ecules into infinite chains and π-π contacts between the benzene rings and between the pyrrole and benzene rings [centroid-centroid distances = 3.374 (1) and 3.730 (1) Å, respectively] may further stabilize the structure. A weak C - H⋯π inter-action is also present.