Propane sultone → 3-{[(1S)-1-(hydroxymethyl)-3-methylbutyl]amino}-1-propanesulfonic acid

To a solution of L-(+)-leucinol (5.0 g, 42.8 mmol) in THF (65 mL) was slowly added 1,3-propanesultone (4.85 g, 40.7 mmol in THF (10 mL)). The solution was stirred at reflux for 2 hours. The reaction was cooled to room temperature. The solid was collected by filtration and washed with acetone (2×50 mL). The solid was dissolved in 50% water/EtOH (400 mL). Dowex Marathon C ion exchange resin (strongly acidic) was added to the solution. The suspension was stirred for 15 minutes before the resin was removed by filtration. The filtrate was evaporated under reduced pressure. The solid was suspended in acetone (150 mL), filtered and dried in the vacuum oven (50° C.), affording the title compound (6.11 g, 63%). 1H NMR (D2O, 500 MHz) δ ppm 3.77 (m, 1H), 3.59 (m, 1H), 3.23 (m, 1H), 3.13 (m, 2H), 2.90 (m, 2H), 2.02 (m, 2H), 1.53 (m, 2H), 1.35 (m, 1H), 0.81 (d, 3H, J=16.1 Hz). 13C (D2O, 125 MHz) δ ppm 58.72, 58.00, 48.17, 43.54, 35.96, 24.34, 22.53, 21.62, 20.89. [α]D=+16.6° (c=0.0022 in water), ES-MS 240 (M+1).