4-Hydr­oxy-3-[(2E)-3-(3,4,5-trimethoxy­phen­yl)prop-2-eno­yl]-2H-chromen-2-one

A new chalcone of the coumarin, C21H18O7, containing an annulated α-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)°. The crystal packing involves dimers inter­connected by C—H⋯O hydrogen bonding