THE SYNTHESIS AND CRYSTAL STRUCTURE OF 5-ACETYL-2'-DEOXYURIDINE

Article abstract of DOI:10.1016/0040-4020(80)87029-3

5-Acetyl-2'-deoxyuridine (1) has been synthesised by treating 2'-deoxy-5-ethynyluridine with dilute sulphuric acid.Condensation of the trimethylsilyl derivate of 5-acetyluracil with 2-deox-3,5-di-O-p-toluoyl-α-D-erythropentofuranosyl chloride gave a mixture of α- and β-anomeric blocked nucleosides from which the α-anomer was isolated and the p-toluoyl groups removed to give 5-acetyl-1-(α-D-2-deoxyerythropentofuranosyl)uracil.Only a poor yield of the β-anomer (1) was obtained by this procedure.The UV spectra and m.p. obtained for 1 differed from the values quoted in the literature.The crystals of 1 are monoclinic, space group P2₁, with a=9.525, b=12.16, c=5.22 Angstroem, β=92.03 deg and two molecules in the unit cell.The structure was refined by least-squares calculations to R 3.4percent for 1426 observed counter amplitudes.The pyrimidine ring is essentially planar with the acetyl group inclined at 6 deg to it.The sugar ring has the highly unusuael C(4')-exo conformation and the arrangement about C(4')-C(5') is such that O(5') is oriented gauche with respect to both O(1') and C(3').The glycosidic torsion angle O(1')-C(1')-N(1)-C(6) is 56 deg (anti conformation).