S-methyl chlorothioformate → (3-chloro-pyrazin-2-ylmethyl)-thiocarbamic acid S-methyl ester

To a suspension of C-(3-chloro-pyrazin-2-yl)-methylamine hydrochloride salt (5.13 g, 0.0285 mol) in DCM (60 mL) were added N,N-diisopropylethylamine (15 mL, 0.085 mol) and carbonochloridothioic acid, S-methyl ester (3.15 g, 0.0285 mol) at 0° C. 5 min later, the mixture was warmed to rt and kept at rt overnight. The mixture was diluted with DCM (50 mL), washed with water (30 mL), sat. aq. NaHCO3 (2×30 mL), brine (30 mL), and dried over anhydrous sodium sulfate. The crude product was purified by silica gel chromatography (Hex EtOAc=70:30→50:50) to give the title compound as a light-yellow solid, 4.4 g, 71% yield. 1H NMR (CDCl3, 400 MHz) δ 2.41 (s, 3H), 4.76 (d, J=4.6 Hz, 2H), 6.67 (br s, 1H), 8.34 (d, J=2.5 Hz, 1H), 8.48 (d, J=2.5 Hz, 1H).