Crystal structure of 7-[(2E)-2-benzyl-idene-3-oxobut-oxy]-4-methyl-2H-chromen-2-one.

Two independent mol-ecules (A and B) comprise the asymmetric unit of the title compound, C21H18O4. There are significant conformational differences between the mol-ecules relating in particular to the relative orientation of the 3-oxo-2-(phenyl-methyl-idene)but-oxy substituent with respect to the superimposable chromen-2-one residues. To a first approximation, the substituents are mirror images; both are approximately perpendicular to the chromen-2-one fused ring system with dihedral angles of 88.50†(7) (A) and 81.96†(7)° (B). Another difference between the independent mol-ecules is noted in the dihedral angles between the adjacent phenyl and but-3-en-2-one groups of 8.72†(12) (A) and 27.70†(10)° (B). The conformation about the ethene bond in both mol-ecules is E. The crystal packing features C-H⋯O, C-H⋯π(ar-yl) and π-π [Cg⋯Cg = 3.6657†(8) and 3.7778†(8)†à ] stacking inter-actions, which generate a three-dimensional network.