3-Hy­droxy-2,2-bis­(1H-pyrazol-1-yl)­cyclo­penta­none

The title compound, C(11)H(12)N(4)O(2), was unexpectedly obtained in the reaction of α,α′-disubstituted cyclo­penta­none with 1,1,3,3-tetra­meth­oxy­propane in the presence of dioxane saturated with HCl. It belongs to a previously unknown class of gem-bihetaryl ketones which may be useful for screening of new substances with biological activity. In the studied structure, the cyclo­penta­none moiety adopts an envelope conformation, with the hy­droxy-bearing C atom as the flap [deviation from basal plane = 0.643 (3) Å]. The dihedral angle between the two pyrazole rings is 80.02 (8)°. In the crystal, inversion dimers are formed via a pair of O—H⋯N hydrogen bonds.