7,8,9,10-Tetrahydro-2-methylcyclohepta[b]indol-6(5H)-one

The title compound, C14H15NO, was synthesized from 2-hydroxymethylenecycloheptanone via a Japp–Klingemann acid-catalyzed cyclization. The seven-membered ring exhibits a slightly distorted envelope conformation. N—H⋯O hydrogen bonds form a centrosymmetric dimer; C—H⋯O hydrogen bonds and π–π stacking interactions (the centers of the atoms involved in the stacking interaction are separated by 3.504 Å) give rise to another type of centrosymmetric dimer. In combination, these interactions create a stair-like chain of molecules that interacts only loosely with neighboring chains via van der Waals interactions and weak C—H⋯π contacts.