Under N2 atmosphere, 1.0 g 4,N-diethyl-4,5-dihydro-pyrazole-1-carboxamidine was dissolved in 15 mL dry DCM, and 1.14 mL DiPEA and 1.31 g of 3-(chlorosulfonyl)benzoic acid were added. The mixture was stirred overnight at room temperature and evaporated to dryness. The residue was purified by flash chromatography (first column with DCM/MeOH/acetic acid 84:15:1; second column with DCM/MeOH/NH4OH 84:15:1) to yield 0.08 g (4%) of an off-white powder. 1H NMR (400 MHz, CDCl3) δ 0.90 (t, J=7.4 Hz, 3H), 1.14 (t, J=7.2 Hz, 3H), 1.38-1.62 (m, 2H), 3.02-3.18 (m, 1H), 3.27-3.62 (m, 3H), 3.89-4.17 (m, 1H), 6.94 (s, 1H), 7.26 (t, J=7.8 Hz, 1H), 7.89 (d, J=7.8 Hz, 1H), 8.05 (d, J=7.8 Hz, 1H), 8.49 (s, 1H).
