Sodium-hydroxide-catalyzed condensation of di-p-methyl- and di-p-methoxybenzil with acetone derivatives was investigated in methanol. Di- and trisubstituted products were obtained as cyclopentenones, while tetraaryl-substituted systems were isolated as cyclopentadienones. The structures of the products were identified by elemental analysis, infrared (IR), nuclear magnetic resonance (1H NMR), and mass spectroscopy. The solid-state structure of 4-hydroxy-3,4-bis(4-methoxyphenyl)-5,5-dimethyl-2-cyclopenten-1-one was further studied by single-crystal X-ray diffraction analysis. The title compound crystallizes in an orthorhombic space group and intermolecular O–HO and C–HO hydrogen bonds stabilize the crystal lattice.
