Crude compound 59 (1.69 g) was suspended in CH2Cl2 (200 mL). Then acetone (4 mL) and STAB (3.4 g) were added. The mixture was stirred for 24 h (TLC monitoring, eluent: CHCl3-MeOH, 9:1), then poured into an aqueous NaHCO3 solution. Then, another portion of CH2Cl2 and MeOH was added. The organic layer was separated, evaporated, washed with MeCN and ether. Yield of Example 8: 0.759 g. For the preparation of hydrochloride, the isolated product was suspended in a mixture of CH2Cl2 and MeOH, then a solution of HCl in dioxane was added. The resulting mixture was evaporated to dryness, and ethanol was added to the residue. The ethanolic solution was refluxed and cooled, and the precipitate was filtered. Yield of compound Example 8 hydrochloride: 0.684 g. 1H-NMR (DMSO-D6) spectrum: δ 1.24 (6H, d, J=6.6 Hz); 2.77-2.79 (4H, m); 3.34-3.43 (3H, m); 3.81-3.84 (4H, m); 4.91 (2H, t, J=7.3 Hz); 7.83 (2H, d, J=8.6 Hz); 7.91 (2H, d, J=8.6 Hz); 9.11 (2H, br. s). ELSD: 100%, ESI-MS: m/z 360 [M+H].+
