3-Methyl-1,2,3,4,5,6,1′,2′,3′,4′- decahydrospiro[benz[f]isoquinoline-1,2′-naphthalen]-1′-one

The title compound, C23H23NO, is the product of a tandem transformation of the double Mannich base bis(1-oxo-1,2,3,4-tertrahydro- 2-naphthoylmethyl)amine hydrochloride in HBr solution upon heating. The tetrahydropyridine ring has a non-symmetrical half-chair conformation, whereas the cyclohexadiene and cyclohexene rings adopt non-symmetrical half-boat conformations. The dihedral angle between the planes of the terminal benzene rings is 62.85(6)°. The N atom has a trigonal-pyramidal geometry [sum of the bond angles = 332.4(3)°]. In the crystal, molecules form [001] chains via weak non-classical C-H⋯N hydrogen bonds. The chains are stacked along the b axis.