An unusual syn conformation of 5-formyluracil stabilized by supramolecular interactions
Gustavo Portalone1, Marcello Colapietro
1Chemistry Department, Sapienza University of Rome, P.le A. Moro 5, I-00185 Rome, Italy. g.portalone@caspur.it
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.
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