Stage 1 - Coupling Reaction: Under nitrogen protection, piperidine-4-methanol (2.48 g, 21.55 mmol) was stirred with K2CO3 (8.9 g, 64.65 mmol) in a 1:1 solvent mixture of DMF/MeCN (20 mL) for 10 min at room temperature. Subsequently, ethyl 2-methylsulfonyl-5-pyrimidinecarboxylate (5 g, 21.55 mmol) was added and the reaction continued to be stirred for 20 min. After completion of the reaction, the reaction mixture was diluted with deionized water (100 mL) and extracted with ethyl acetate (2 x 100 mL). The organic layers were combined, dried with anhydrous MgSO4 and concentrated under reduced pressure to remove the solvent to afford the orange solid product ethyl 2-(4-hydroxymethylpiperidin-1-yl)pyrimidine-5-carboxylate (5.70 g, 99% yield). Mass spectrometry analysis showed m/z = 266 [M + H]+. The product was used directly in subsequent steps without further purification.
