2′,3′-O-Isopropylidene-5-[(N-trifluoroacetyI)methoxycarbonylmethylaminomethyl]uridine (5) and 2′,3′-0-isopropylidene-5-ethoxycarbonylmethoxyuridine (6) have been prepared using as the substrates 2′,3′-O-isopropylidene-5-chloromethyluridine (11) and 2′,3′-O-isopropylidene- 5-hydroxyuridine (8). respectively. The transformation of 5 and 6 into respective 2,5′-anhydro-nucleosides 16 and 10 followed by treatment of 16 and 10 with liquid hydrogen sulphide/pyridine system produces 2′,3′-O-isopropylidene-5-[(N-trifluoroacetyl)methoxycarbonylmethylamino- methyl]-2-thiouridine (17) and 2′,3′-O-isopropylidene-5-ethoxycarbonylmethoxy-2-thiouridine (18). The acid catalysed methanolysis of 6 and 18 yields 5-methoxycarbonylmethoxyuridine (4) and its 2-thioanalogue 4a, while refluxing of 5 and 17 with 50% acetic acid gives 5-[(N-tri-fluoroacetyl)methoxycarbonylmethylaminomethyl]uridine (2) and its 2-thioanalogue 2a