Chemoselective O -Alkylation of 4-(Trifluoromethyl)pyrimidin-2(1 H )-ones Using 4-(Iodomethyl)pyrimidines.

This study reports two strategies for preparing O -alkyl derivatives of 6-substituted-4-(trifluoromethyl)pyrimidin-(1 H )-ones: a linear protocol of alkylation, using a CCC -building block followed by [3 + 3]-type cyclocondensation with 2-methylisothiourea sulfate and a convergent protocol based on direct alkylation, using 4-(iodomethyl)-2-(methylthio)-6-(trihalomethyl)pyrimidines. It was found that the cyclocondensation strategy is not feasible; thus, the direct chemoselective O -alkylation was performed, and 18 derivatives of the targeted pyrimidines were obtained in 70-98% yields. The structure of the products was unambiguously determined via single crystal X-ray analyses and two-dimensional nuclear magnetic resonance experiments.