variety of pyrimidine C-nucleosides bearing branched-chain sugars can be synthesized starting from adequately substituted (1R*,6S*,7S*,8R*)-7,8-isopropylidenedioxy-3,9-dioxabicyclo[4.2.1]nonan-4-ones. The general procedure consists of condensation with t-butoxybis(dimethylamino) methane, giving the corresponding α-dimethylaminomethylene lactones, base-catalyzed heterocycle formation with urea, thiourea