he molecule of the title compound, C₁₉H₂₇NO₃, is essentially planar, with all non-H atoms within 0.2 Å of the nine-membered indole plane, except for the three tert-butyl C atoms. The C₅ pentyl chain is in an extended conformation, with three torsion angles of 179.95 (13), 179.65 (13) and -178.95 (15)° (the latter two angles include the C atoms of the C5 chain only). Three intramolecular C-H...O=C contacts are present (C...O < 3.05 Å and C-H...O > 115°), and an intermolecular C-H...O=C contact and π-π stacking complete the intermolecular interactions.