4-Hydr-oxy-3-mesityl-1-oxaspiro-[4.4]non-3-en-2-one.

In the title compound, C(17)H(20)O(3), the five-membered cyclo-pentyl ring displays an envelope conformation, with the atom at the flap position 0.538†(3)†à out of the mean plane formed by the other four atoms. The dihedral angle between the benzene and furan rings is 63.34†(15)°. In the crystal structure, mol-ecules are linked through inter-molecular O-H⋯O hydrogen bonds, forming a zigzag chain along [101].