General procedure for the synthesis of tert-butyl 4-(pyrimidin-2-yloxy)-piperidine-1-carboxylate from 2-chloropyrimidine and N-Boc-4-hydroxypiperidine: N-Boc-4-hydroxypiperidine (10 g, 50 mmol) was dissolved in tetrahydrofuran (200 mL) and the solution was cooled to 5 °C. Under stirring, sodium hydride (60% mineral oil dispersion, 2.5 g, 65 mmol) was added in batches and stirring was continued for 30 min keeping the reaction temperature at 5 °C. Subsequently, 2-chloropyrimidine (11.4 g, 99 mmol) was added and the reaction mixture was stirred at room temperature for 18 hours. After completion of the reaction, the mixture was filtered and the filtrate was concentrated under reduced pressure. The concentrated residue was partitioned between ethyl acetate and water. The organic layer was separated, dried with anhydrous magnesium sulfate and subsequently concentrated under reduced pressure. Finally, the residue was recrystallized in diisopropyl ether (50 mL) to afford tert-butyl 4-(pyrimidin-2-yloxy)-piperidine-1-carboxylate in 68% (9.5 g) yield.
