Reaction Steps
(2R,3S)-3-(4-Fluoro-benzylamino)-bicyclo[2,2,2]octane-2-carboxylic acid methyl ester (93 mg, 0.32 mmol) was dissolved in anhydrous N,N-dimethylformamide (4 mL). (7-Methanesulfonylamino-1,1-dioxo-1,4-dihydro-1λ6-benzo[1,2,4]thiadiazin-3-yl)-acetic acid (prepared as described in Example 1g, 107 mg, 0.32 mmol) was added followed by N-methylmorpholine (74 μL, 0.67 mmol). The mixture was stirred until everything dissolved, approximately 5 min. 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (65 mg, 0.34 mmol) was added and the mixture was stirred at 25° C. for 16 h. The reaction was quenched via addition of saturated aqueous sodium bicarbonate solution (20 mL). The mixture was extracted with ethyl acetate (3×30 mL). The combined organic layers were washed with saturated aqueous brine solution (20 mL), dried over magnesium sulfate, filtered, and concentrated in vacuo to afford a golden oil. The oil was dissolved in ethanol (5 mL). A 21 wt. % solution of sodium ethoxide in ethanol (0.36 mL, 0.96 mmol) was added. The reaction was refluxed for 16 h. The reaction was quenched via the addition of 1.0 M aqueous hydrochloric acid solution (10 mL). The mixture was extracted with ethyl acetate (3×20 mL). The organic layer was further washed with saturated sodium bicarbonate solution (2×20 mL), saturated aqueous brine solution (20 mL), dried over magnesium sulfate, filtered, and concentrated in vacuo to afford a clear oil. Purification by flash column chromatography (Teledyne Isco RediSep column; 0 to 20% ethyl acetate in dichloromethane) afforded the desired product, N-{3-[(2S,7R)-3-(4-fluoro-benzyl)-6-hydroxy-4-oxo-3-aza-tricyclo[6.2.2.02,7]dodec-5-en-5-yl]-1,1-dioxo-1,4-dihydro-1λ6-benzo[1,2,4]thiadiazin-7-yl}-methanesulfonamide (0.11 g, 0.19 mmol, 59%), as a white powder. 1H NMR (400 MHz, DMSO-d6) δ: 1.39 (2H, d, J=8.0 Hz), 1.54-1.59 (8H, m), 1.91 (1H, s), 2.14 (1H, s), 3.06 (3H, s), 3.75 (1H, d, J=11.6 Hz), 4.28 (1H, d, J=15.2 Hz), 5.03 (1H, d, J=15.6 Hz), 7.13-7.17 (2H, m), 7.34-7.37 (2H, m), 7.50-7.60 (3H, m), 10.18 (1H, s). LC-MS (ESI) calcd for C26H27FN4O6S2 574.64, found 575.1 [M+H+]. m.p.: 203.8-205.7° C. ee=94.4% [HPLC-analysis: Chiralpak AS-RH 4.6×250 mm, 5 micron, 0.8 mL/min, 310 nm].
