Addition of 2-cyanoethyl diisopropyl chlorophosphoramidite to DMT protected 2'-desoxy-2'-fluoro-5-vinyl-uridine. 10 (0.88 g), and dimethylaminopyridine (0.14 g, 1.14 mmol) were dissolved in 50 mL of dry DCM, diisopropylethylamine (0.84 mL, 6.51 mmol) and 2-cyanoethyl-diisopropylchlorophosphoramidite (0.83 mL, 3.50 mmol) were added. Under an atmosphere of nitrogen, the mixture was then stirred at room temperature for 2 hours. After the DCM was removed in vacuo a thick yellow oil was obtained (13) (1.63 g). P NMR was run on the product, to prove the addition of the phosphoramidite group. No other analysis was run on it because of the air sensitive nature of the product. P NMR (DMSO-d 6 capillary in DCM): δ 139.00 (s, 1P).