A solution of borane in THF (1M, 0.5 mL, 0.5 mmol) was added to a solution of 4-[3-(4-butyl-piperidin-1-yl)-propyl]-6-methyl-4H-benzo[1,4]oxazin-3-one (50 mg, 0.15 mmol) in THF (6 mL). The reaction mixture was stirred at 40° C. for 16 h then aqueous HCl (4M, 10 mL) was added drop wise at room temperature. The reaction mixture was stirred for 16 h then concentrated in vacuo. A solution of K2CO3 (0.5 g) in water (5 mL) was added and the product was extracted with dichloromethane (2×10 mL). The organic layer was dried (Na2SO4) and concentrated in vacuo. The product was purified on an Isco CombiFlash Sq 16× (4 g silica column, eluting 0-20% ethyl acetate in heptanes+1% Et3N). Yield: 29.2 mg, 56%. HPLC-MS: M+1+=373.5 (UV/MS(%)=95/90). 1H NMR (400 MHz, CDCl3): δ=0.90 (3H, t), 1.18-1.35 (9H, m), 1.68 (2H, broad d), 1.78 (2H, quin.), 1.89 (2H, broad t), 2.24 (3H, s), 2.35 (2H, t), 2.89 (2H, broad d), 3.27 (2H, t), 3.31 (2H, t), 4.19 (2H, t), 6.39 (1H, broad d), 6.52 (1H, broad s), 6.66 (1H, d). 13C NMR (CDCl3): δ 14.3, 21.4, 23.1, 24.2, 29.3, 32.8 (2C), 36.1, 36.6, 47.4, 49.3, 54.5 (2C), 56.5, 64.7, 113.0, 116.2, 117.7, 131.1, 135.3, 142.0.
