tert-Butyl {2-[2-({3-[2-(tetrahydro-2H-pyran-2-yloxy)ethoxy]pyridin-2-yl}oxy)ethoxy]ethyl}carbamate (from Step 1; 0.74 g, 1.7 mmol) was suspended in 2 M HOAc (5 mL) and acetonitrile (1 mL) and heated at 50° C. for two days. The solution was neutralized with concentrated aqueous ammonia. Brine was added (3 mL) and the mixture was extracted with CHCl3 (×3). The combined organic phases were dried (MgSO4) and the solvent was removed under reduced pressure. The remaining oil was dissolved in dry DMSO (10 mL), potassium tert-butoxide (0.36 g, 3.2 mmol) was added followed by tert-butyl (3R)-4-(3-chloropyrazin-2-yl)-3-methylpiperazine-1-carboxylate (from Example 5; 0.59 g, 1.9 mmol) and the mixture was heated at 50° C. for 20 minutes. The reaction mixture was diluted with water/brine (90:10) and extracted with CHCl3 (×3). The combined organic phases were dried (MgSO4), the solvent was removed under reduced pressure and the remaining oil was chromatographed on a column of silica with hexane/EtOAc (70:30) as eluent to give 0.43 g (40%) of the title compound as a colorless oil. LC-UV purity: system (A) 100%. HRMS m/z calcd for C30H46N6O8 (M)+ 618.3377. found 618.3381. Step 3: {2-[2-({3-[2-({3-[(2R)-2-Methylpiperazin-1-yl]pyrazin-2-yl}oxy)ethoxy]pyridin-2-yl}oxy)ethoxy]ethyl}amine, bis(trifluoroacetate).
