摘要:
                                Mercuric-catalyzed hydrolysis of acetylated L-rhamnal 1 gives an alpha,beta-unsaturated aldehyde 2.  1,4-Addition of DBU-phthalimide salt with concomitant acetyl shift resulted in L-ribo and L-arabino isomers of 5-O-acetyl-2,3,6-trideoxy-3-phthalimido-hexofuranose 3 and 4.  After acetylation at the anomeric center, coupling with silylated thymine resulted in three new nucleosides, with L-acosamine and L-ristosamine of furanose configuration as the carbohydrate moiety.  The target compounds have been evaluated for their antiviral activity against HIV and HSV-1.