Dimethyl 2,2′-[(4-oxo-2-phenyl-4H-chromene-5,7-di­yl)di­oxy]diacetate: a less densely packed polymorph

The title mol­ecule, C(21)H(18)O(8), crystallizes in two crystal polymorphs, see also Nallasivam, Nethaji, Vembu & Jaswant [Acta Cryst. (2009), E65, o312–o313]. The main difference between the two polymorphs is in the conformation of the oxomethyl­acetate groups with regard to the almost planar [total puckering amplitude 0.047 (2) Å] chromene ring. In the title compound, the best planes of the oxomethyl­acetate groups through the non-H atoms are almost perpendicular to the chromene ring [making dihedral angles of 89.61 (6) and 80.59 (5)°], while in the second polymorph the mol­ecules are close to planar. Both crystal structures are stabilized by C—H⋯O.