Synthesis and structural characterization of the C-6 fluoroalkylated pyrimidine derivatives

C-6 substituted fluoroalkenyl 2,4-dimethoxypyrimidine derivative (4) was synthesized by lithiation of 2,4-dimethoxy-6-methylpyrimidine (3) and subsequent reaction of thus obtained organolithium intermediate with ethyl pentafluoropropionate. The novel 2,4-pyrimidinedione containing 3,3,4,4,4-pentafluoro-1-butenyl side chain (5) was prepared by demethoxylation of 4 using sodium iodide and chlorotrimethylsilane. The structures of 4 and 5 were confirmed by 1H, 13C and 19F NMR spectra, as well as IR spectra. The structure of 4 was also unambiguously confirmed by X-ray crystal structure analysis. The molecules of 4 are weakly linked by aromatic π···π stacking interactions into infinite chains parallel to the a axis.