(3R,4R)-(-)-6-O-Benzyl -1-deoxy-1-(dimethyl- phosphono)-3, 4-O-isopropylidene-D-ribo-hexulose 6-O-Benzyl-1-deoxy-1-(dimethoxyphosphoryl)-3,4-O-(1-methylethylidene)hex-2-ulose AIDS-136727 AIDS136727 NSC639627