Syntheses of Pyridine C-Nucleosides as Analogues of the Natural Nucleosides dC and dU

The syntheses of four pyrimidine C-nucleosides are described. These derivatives are designed as mimics of dC and
dU, and in that respect, each can form two hydrogen bonds
with complementary dG or dA residues. The minor groove
O2 carbonyl in each derivative is replaced by a fluorine or
a methyl group. The key carbon−carbon bond connecting
the heterocycle to the carbohydrate is formed using a Heck-type palladium-mediated coupling reaction.