title: An unusual syn conformation of 5-formyluracil stabilized by supramolecular interactions.
abstract: The asymmetric unit of the amino-oxo tautomer of 5-formyluracil (systematic name: 2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-carbaldehyde), C(5)H(4)N(2)O(3), comprises one planar amino-oxo tautomer, as every atom in the structure lies on a crystallographic mirror plane. At variance with all the previously reported small-molecule crystal structures containing the 5-formyluracil residue, the formyl substituent in the title compound exhibits an unusual syn conformation. The molecules are linked into planar sheets parallel to the bc plane by a combination of six N-H...O and C-H...O hydrogen bonds. Four of the hydrogen bonds are utilized to stabilize the formyl group in the syn conformation.
authors.affiliation: Chemistry Department, Sapienza University of Rome, P.le A. Moro 5, I-00185 Rome, Italy. g.portalone@caspur.it
authors.forename: Gustavo
authors.initials: G
authors.lastname: Portalone
authors.forename: Marcello
authors.initials: M
authors.lastname: Colapietro
mesh_terms: D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008968:Molecular Conformation; D009153:Mutagens / Q000737:chemistry*; D013237:Stereoisomerism; D014498:Uracil / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D009153:Mutagens; C007777:5-formyluracil; D014498:Uracil