Step 1: Tert-butyl (4-bromopyridin-2-yl) carbamate (0.25 g, 0.915 mmol) was dissolved in DMF (5 ml) at 0 °C. To this solution, NaH (60% oil solution, 0.073 g, 1.83 mmol) was slowly added, keeping the reaction mixture stirred at 0°C for 15 min. Subsequently, methyl iodide (0.26 g, 1.37 mmol) was added at the same temperature. The reaction mixture was transferred to room temperature and stirring was continued for 1 hour. After completion of the reaction, the mixture was poured into ice-cold water (20 ml) and extracted with EtOAc (2 x 15 ml). The organic layers were combined, washed with brine (20 ml) and then dried over Na2SO4. After filtration, the organic phase was concentrated under reduced pressure to afford the crude product (tert-butyl (4-bromopyridin-2-yl)(methyl)carbamate (0.25 g, 0.87 mmol), which was used in the subsequent reaction without further purification.The LCMS analysis (Method A) showed a retention time of 2.50 min, and the mass spectra (MS: ES+) observed the peaks with m/z of 230.9 and 232.9 (M -56) ion peaks.
