1,3,4,8-Tetraphenyl-7-oxa-1,2-diazaspiro[4.4]nona-2,8-dien-6-one

In the title compound, C₃₀H₂₂N₂O₂, the pyrazoline ring deviates slightly from an ideal envelope conformation. It is substituted by three planar phenyl rings, inclined to it at angles of 89.8 (1), 14.1 (1) and 7.3 (1)°. The substituted phenyl rings are in equatorial and axial positions with respect to the pyrazoline ring. The lactone ring is essentially planar but the keto group O atom deviates from the least-squares plane through the ring atoms by -0.130 (1) Å. The lactone ring has one phenyl substituent, adopting an axial position and inclined at an angle of 11.3 (1)°. The dihedral angle between the pyrazoline and lactone rings is 87.6 (1)°. The crystal structure is stabilized by weak intermolecular hydrogen bonds.

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