title: Crystal structure of 7-[(2E)-2-benzyl-idene-3-oxobut-oxy]-4-methyl-2H-chromen-2-one.
abstract: 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) Å] stacking inter-actions, which generate a three-dimensional network.
authors.affiliation: Departmento de Física, Universidade Federal de São Carlos, 13565-905 São Carlos, SP , Brazil.
authors.forename: Ignez
authors.initials: I
authors.lastname: Caracelli
authors.affiliation: Departmento de Química, Universidade Federal de São Carlos, 13565-905 São Carlos, SP, Brazil.
authors.forename: Julio
authors.initials: J
authors.lastname: Zukerman-Schpector
authors.affiliation: Instituto de Química, Universidade Estadual de Campinas, C.P. 6154, 13083-970 Campinas, SP, Brazil.
authors.forename: Paulo J S
authors.initials: PJ
authors.lastname: Moran
authors.affiliation: Instituto de Química, Universidade Estadual de Campinas, C.P. 6154, 13083-970 Campinas, SP, Brazil.
authors.forename: Bruno R S
authors.initials: BR
authors.lastname: de Paula
authors.affiliation: Department of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Edward R T
authors.initials: ER
authors.lastname: Tiekink
keywords: chromen-2-one; conformation; crystal structure