Crystal structure of 7-[(2E)-2-benzylidene-3-oxobutoxy]-4-methyl-2H-chromen-2-one

Abstract

Two independent molecules (A and B) comprise the asymmetric unit of the title compound, C21H18O4. There are significant conformational differences between the molecules relating in particular to the relative orientation of the 3-oxo-2-(phenylmethylidene)butoxy 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 molecules 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 molecules is E. The crystal packing features C—H...O, C—H...π(aryl) and π–π [Cg...Cg = 3.6657 (8) and 3.7778 (8) Å] stacking interactions, which generate a three-dimensional network.

Keywords

• crystal structure
• chromen-2-one
• conformation