(2S)-2-[1-(2,4-Difluoro-5-iodophenyl)-2-deoxy-beta-D-ribofuranos-5-yloxy]-8-methyl-4H-1,3,2-benzodioxaphosphole 2-oxide.

The title compound, C(19)H(18)F(2)IO(6)P, prepared as a potential antiviral and anticancer agent from 3-methylsalicylchlorophosphane and 1-(2,4-difluoro-5-iodophenyl)-2-deoxy-beta-D-ribofuranose, is one of a 1:1 mixture of two diastereomers. The diastereomers differ in their configuration, S or R, at the asymmetric phosphorus center. X-Ray crystallographic analysis of the title compound has determined the absolute configuration at the asymmetric P center to be S.