(3S)-3-(1-Methylethyl)-1-[3-(methyloxy)-4-nitrophenyl]piperazine (0.355 g, 1.27 mmol) was dissolved in 15 mL of dioxane with stirring. Methyl vinyl sulfone (0.34 mL, 3.88 mmol) was added via syringe. The reaction was heated to 60° C. for 2.5 days. Additional methyl vinyl sulfone (0.68 mL, 7.76 mmol) was added, and the heat was increased to 90° C. The reaction was maintained at that temperature for one week. The reaction was cooled to rt and concentrated onto silica gel. Purification by flash chromatography afforded the title compound of step G (0.383 g, 0.994 mmol, 78%). 1H NMR (400 MHz, DMSO-d6) δ 7.84 (d, J=9.5 Hz, 1H), 6.53 (dd, J=9.5, 2.4 Hz, 1H), 6.40 (d, J=2.4 Hz, 1H), 3.86 (s, 3H), 3.77 (d, J=12.5 Hz, 1H), 3.66 (br. s., J=12.5 Hz, 1H), 3.28-3.39 (m, 1H), 3.13-3.24 (m, 1H), 3.00-3.13 (m, 2H), 2.88-3.00 (m, 5H), 2.77-2.88 (m, 1H), 2.39-2.51 (m, 1H), 2.17-2.26 (m, 1H), 1.93-2.07 (m, 1H), 0.96 (d, J=6.8 Hz, 3H), 0.85 (d, J=6.8 Hz, 3H).
