A solution of (S)-tert-butyl 2,2,4-trimethyl-4-(2-(4-(octyloxy)-3-(trifluoromethyl)-benzoyl)hydrazinecarbonyl)oxazolidine-3-carboxylate (14a) (156 mg, 0.27 mmol) in methanol (5 mL) was treated with p-toluenesulfonic acid monohydrate (259 mg, 1.36 mmol) at 70° C. for 2 hours. The reaction mixture was then cooled to room temperature and purified by prep HPLC on a C8(2) column ((Luna, 5μ, 100×21.10 mm) with acetonitrile-H2O (0.1% TFA) as mobile phase and gradient 30-98% in 20 min. The title compound was obtained as the bis-TFA salt (36 mg, 20%). MS (ESI): 432.00 (MH+); 1H NMR (400 MHz, DMSO-d6) δ 8.21 (dd, 1H, J=2.0 Hz, J=8.8 Hz), 8.15 (d, 1H, J=2.0 Hz), 8.09 (br s, 2H), 7.45 (d, 1H, J=8.8 Hz), 5.96 (t, 1H, J=4.8 Hz), 4.21 (t, 2H, J=6.4 Hz), 3.81 (dd, 1H, J=11.2 Hz, J=5.2 Hz), 3.73 (dd, 1H, J=11.2 Hz, J=5.2 Hz), 1.76 (m, 2H), 1.66 (s, 3H), 1.44 (m, 2H), 1.28 (m, 8H), 0.86 (t, 3H, J=6.8 Hz).
