Abstract
A new chalcone of the coumarin, C21H18O7, containing an annulated alpha-pyrone ring, was obtained by condensation of the borate complex of acyl(hydroxy) coumarin with trimethoxybenzaldehyde. The structure exhibits intramolecular hydrogen bonding between the hydroxyl oxygen and the ketonic oxygen in the coumarin group. The bicyclic coumarin fragment and the benzene ring form a dihedral angle of 17.1 (4)degrees. The crystal packing involves dimers interconnected by C-H center dot center dot center dot O hydrogen bonding.