tert-Butanol → tert-Butyl (5-methylpyrazin-2-yl)carbamate

Participants

Reaction Conditions

Reaction Steps

To solution 5-methylpyrazine-2-carboxylic acid (2.5 g, 18.1 mmol), tert-butanol (6.92 mL, 72.4 mmol), Et3N (3.78 mL, 27.1 mmol) in 1,4-dioxane (12.5 mL) at 95° C. was dropwise added diphenylphosphoryl azide (DPPA, 3.23 mL, 18.1 mmol), and the reaction was heated at 95° C. for 1.5 h, followed by a 2nd portion of DPPA (1 mL, 5.6 mmol) and heated for additional 1.5 h. The reaction mixture was cooled down, concentrated and the residue was diluted with EtOAc (50 mL), washed with water (30 mL), 3 M NaOH (30 mL), sat. NaHCO3 (30 mL) and brine (30 mL), dried over Na2SO4, and concentrated. The residue was purified by flashed chromatography on silica gel eluting with gradient EtOAc/CH2Cl2 (0-20%) to afford tert-butyl 5-methylpyrazin-2-ylcarbamate as white solid. LCMS (m/z): 210.1 (MH+), 0.69 min; 1H NMR (400 MHz, CDCl3) δ ppm 9.17 (s, 1H), 8.09 (s, 1H), 7.75 (br. s., 1H), 2.51 (s, 3H), 1.56 (s, 9H).

Provenance & Evidence