“…Preparation of 5-alkynyluridines was carried out from acyl-protected 5-iodouridines (1a,b) [8,63] and the appropriate terminal alkyne in the presence of catalytic amounts of Pd(PPh 3 ) 4 , copper(I) iodide, triethylamine, in DMF, and at room temperature -to avoid cycloisomerization to furopyrimidines (Scheme 1). The modified pyrimidine nucleoside scaffolds, propargyl acetate-substituted 2'-deoxyuridine (R = Ac, 2) and propargyl methyl ether-substituted uridine (R = Me, 3), were obtained in 87% and 61% yield, respectively.…”