Synthesis and Biological Evaluation of (3′<i>S</i>)-3′-Deoxy-3′-Fluoro-3′-<i>C</i>-Ethynylcytidine

The novel pyrimidine nucleoside, (3'S)-3'-deoxy-3'-fluoro-3'-C-ethynylcytidine (1) was synthesized from cytidine in seven steps. The key step in the synthesis was the introduction of the tertiary fluorine at the 3'-position. Compound 1 was evaluated in vitro against several RNA viruses.