Crystal structure of rac-(3a′R,9a′R)-3a′-(indol-3-yl)-1′,2′,3′,3a′,4′,9a′-hexahydrospiro[cyclopentane-1,9′-pentaleno[1,2-b]indole] p-xylene hemisolvate

The title compound, C₂₆H₂₆N₂·0.5C₈H₁₀, is the first reported characterized 2:2 product from acid-catalyzed condensation of indole with cyclopentanone and no other 2:2 products were observed. Recrystallization from p-xylene gave the title hemisolvate with the p-xylene molecule located about an inversion center. The terminal pentalene ring is envelope-flap disordered at the C atom farthest from the skeletal indole unit, with a refined occupancy ratio of 0.819 (4):0.181 (4). The major component has this C atom bent away from the spiro-fused cyclopentane ring. In the crystal, molecules are connected by N - H⋯π interactions, forming chains along [100], and N - H⋯π and C - H⋯π interactions, forming chains along [001], which results in the formation of slabs parallel to (010).