title: A pimpinellin monomer and dimer isolated from the roots of Esenbeckia grandiflora.
abstract: X-ray diffraction studies carried out on single crystals of the monomeric, viz. 5,6-dimethoxy-2H-furo[2,3-h][1]benzopyran-2-one, C(13)H(10)O(5), and dimeric, viz. 5,5',6,6'-tetramethoxy-3,3',4,4'-tetrahydro-2H,2'H-3,3':4,4'-bi(furo[2,3-h][1]benzopyran)-2,2'-dione, C(26)H(20)O(10), forms of pimpinellin have revealed that, following cyclodimerization, the carbonyl groups are head-to-head with respect to one another. In the monomer, the heterocyclic ring is planar, but it exhibits a twisted-boat conformation in the dimer. Both the monomer and the dimer interact through C-H...O interactions.
authors.affiliation: Departamento de Química, Universidade Federal de Alagoas, 57072-970 Maceió, AL, Brazil.
authors.forename: P E S
authors.initials: PE
authors.lastname: de Oliveira
authors.forename: L M
authors.initials: LM
authors.lastname: Conserva
authors.forename: C A
authors.initials: CA
authors.lastname: De Simone
authors.forename: M A
authors.initials: MA
authors.lastname: Pereira
authors.forename: V R S
authors.initials: VR
authors.lastname: Malta
authors.forename: D O
authors.initials: DO
authors.lastname: Imbroisi
mesh_terms: D019281:Dimerization; D019684:Magnoliopsida / Q000737:chemistry*; D008730:Methoxsalen / Q000031:analogs & derivatives* / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D018517:Plant Roots / Q000737:chemistry*
chemical_list: C039409:pimpinellin; D008730:Methoxsalen