Palladium-catalyzed synthesis of uridines on polystyrene-based solid supports

In this paper, the solid-phase synthesis of various substituted pyrimidine nucleosides is described starting from 2'-deoxyuridine (1), which has been attached through a base labile linker 2 to polystyrene resins. The utility of the Pd(0) cross-coupling to functionalized pyrimidine nucleosides is expanded herein to include reactions of resin-supported 5-iodo-2'-deoxyuridine (8) under Sonogashira, Stille, Heck, and Suzuki conditions. Upon cleavage with MeONa, a library of 5-substituted pyrimidine nucleosides (10a-e, 11a-c, 12a-e) was obtained in good (under Sonogashira and Stille conditions) to moderate (under Heck or Suzuki conditions) yields and high purity. Except the Suzuki-type reactions, the presented methods exhibit a significant improvement and facilitate the synthetic procedure with respect to purification and yields (determined after filtration over silica gel).