Into a room temperature, stirred solution of (S)-10-[3-(4-methoxybutyl)-piperazin-1-yl]-2-methyl-4H-3-thia-4,9-diaza-benzo[f]azulene (0.031 g, 0.08 mmol), and formaldehyde solution (0.082 mL, 0.10 mmol, 37% in H2O) in dichloroethane (0.5 mL) was added NaHB(OAc)3 (0.026 g, 0.12 mmol) and stirred overnight. Dilute the solution with H2O (20 mL), 1.0 N NaOH (1 mL) and extract with CH2Cl2 (3×40 mL). Dry the combined organic layers over Na2SO4, and filter. Concentrate the mixture under reduced pressure and purify by silica gel chromatography eluting with 10% (33% 2 M NH3 in MeOH/64% EtOH)/CH2Cl2. Combine the purified fractions, concentrate under reduced pressure, and place under vacuum to give the title compound: orange solid (0.014 g), mass spectrum (m/e):399.3 (M+H).
