Reaction Steps
[7-(Methanesulfonylamino-methyl)-1,1-dioxo-1,4-dihydro-1λ6-thieno[2,3-e][1,2,4]thiadiazin-3-yl]-acetic acid (prepared as described in Example 2c; 0.096 g, 0.272 mmol), O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate (0.114 g, 0.300 mmol) and 4-methylmorpholine (0.060 mL, 0.546 mmol) were added sequentially to a solution of rac-2-[(4-fluoro-benzylamino)-methyl]-pentanoic acid ethyl ester (0.073 g, 0.273 mmol) in N,N-dimethylformamide (4 mL) at 25° C. The reaction mixture was stirred at 25° C. for 19 h, and then was concentrated in vacuo. The residue was partitioned between 1.0 M aqueous hydrochloric acid solution (100 mL) and ethyl acetate (2×100 mL). The organic layers were dried over sodium sulfate and were concentrated in vacuo. The residue was dissolved in ethanol (12 mL) at 25° C. A 21 wt. % solution of sodium ethoxide in ethanol (0.531 mL, 1.64 mmol) was added and the reaction mixture was heated to 70° C. for 48 h. After cooling to 25° C., the reaction mixture was partitioned between 1.0 M aqueous hydrochloric acid solution (100 mL) and ethyl acetate (2×100 mL). The organic layers were dried over sodium sulfate and were concentrated in vacuo. The residue was purified by flash chromatography (Teledyne Isco RediSep column; 60-100% ethyl acetate in hexanes) to afford (after trituration with diethylether) rac-N-{3-[1-(4-Fluoro-benzyl)-4-hydroxy-2-oxo-5-propyl-1,2,5,6-tetrahydro-pyridin-3-yl]-1,1-dioxo-1,4-dihydro-1λ6-thieno[2,3-e][1,2,4]thiadiazin-7-ylmethyl}-methanesulfonamide (0.060 g, 0.108 mmol, 39%) as a beige solid. 1H NMR (400 MHz, DMSO-d6) δ: 0.75 (3H, t, J=7.1 Hz), 1.08-1.19 (2H, m), 1.21-1.28 (1H, m), 1.47-1.55 (1H, m), 2.53 (1H, bs), 2.95 (3H, s), 3.18 (1H, dd, J1=3.8 Hz, J2=13.2 Hz), 3.55 (1H, dd, J1=4.5 Hz, J2=12.9 Hz), 4.24 (2H, d, J=6.5 Hz), 4.39 (1H, d, J=14.7 Hz), 4.79 (1H, d, J=14.7 Hz), 7.14-7.18 (2H, m), 7.23 (1H, s), 7.36-7.39 (2H, m), 7.63 (1H, t, J=5.9 Hz). LC-MS (ESI) calculated for C22H25FN4O6S3 556.09. found 557.3 [M+H+].
