Transformations of Griseofulvin in Strong Acidic Conditions – Crystal Structures of 2′-Demethylgriseofulvin and Dimerized Griseofulvin

Abstract

The structure of griseofulvic acid, C₁₆H₁₅ClO₆, at 100 K has orthorhombic (P2₁2₁2) symmetry. It is of interest with respect to biological activity. The structure displays intermolecular O–H···O, C–H···O hydrogen bonding as well as week C–H···π and π ···π interactions. In strong acidic conditions the griseofulvin undergoes dimerization. The structure of dimerized griseofulvin, C₃₄H₃₂C_l2O₁₂·C₂H₆O·H₂O, at 100 K has monoclinic (P2₁) symmetry. The molecule crystallized as a solvate with one ethanol and one water molecule. The dimeric molecules form intermolecular O–H···O hydrogen bonds to solvents molecules only but they interact via week C–H···O, C–H···π, C–Cl···π and π···π interactions with other dimerized molecules.