A 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, or guanidine, and acid ...