Hydrogenate a mixture of (E)-[4-(3-fluoro-6H-dibenzo[b,e]oxepin-11-ylidenemethyl)-2-nitro-phenyl]-((7R,8aR)-hexahydro-pyrrolo[2,1-c][1,4]oxazin-7-yl)-amine (52 g, 0.107 mol), triethylamine (33 mL, 0.237 mol) and 5% platinum on carbon (18 g) in tetrahydrofuran (450 mL) at room temperature at 50 psi for 2 h. Filter off the catalyst, rinse with tetrahydrofuran, and concentrate to obtain a brown foam. Dissolve the foam in anhydrous tetrahydrofuran (500 mL) and cool in an ice bath. Add triphosgene (31.5 g, 0.106 mol) in tetrahydrofuran (450 mL) dropwise over 30 min and stir at room temperature for 16 h. Concentrate the solution, dissolve in 5% methanol in dichloromethane and purify through a short silica gel plug. Concentrate to obtain a brown solid. Suspend the solid in saturated sodium bicarbonate (1.5 L) and stir on the rotary evaporator for one hour. Filter and dry in vacuo. Dissolve in warm 1:1 methanol/dichloromethane (approximately 6 L) and treat with poly (4-vinylpyridine) 2% cross-linked resin (170 g). Stir the slurry for 30 min and filter through diatomaceous earth. Concentrate the filtrate to approximately 1.5 L volume and collect the resulting solids by filtration. Dry at 80° C./20 mm Hg overnight to obtain the title compound as a white solid (38.1 g, 74%). [α]D20−20.5 (c=1.0 in DMSO). 1H NMR (400 MHz, DMSO-d6) δ 1.48 (m, 1H), 2.02 (m, 1H), 2.19 (m, 2H), 2.52 (m, 1H), 2.91 (d, 1H), 3.03 (d, 1H), 3.25 (t, 1H), 3.50 (t, 1H), 3.79 (d, 1H), 3.88 (d, 1H), 4.95 (m, 1H), 5.03 (broad s, 1H), 5.60 (broad s, 1H), 6.59 (m, 2H), 6.78 (m, 2H), 6.97 (s, 1H), 7.02 (d, 1H), 7.25 (t, 1H), 7.38 (t, 1H), 7.48-7.61 (m, 3H), 10.72 (s, 1H, NH). LC-MS m/z 484.0 [M+H]+.
