Reaction Steps
TFAA (15 mg, 0.069 mmol) was slowly added to a 0° C. solution of Example 29 (27 mg, 0.034 mmol) and TEA (12.2 mg, 0.121 mmol) in DCM (0.25 mL). The reaction mixture was then stirred at rt for 1.5 hr. The reaction mixture was concentrated and the residue was partitioned between EtOAc and 10% aqueous Na2CO3. The organic phase was isolated, washed with saturated aqueous NaCl, dried over MgSO4, filtered and concentrated. The crude product was purified by RP prep-HPLC (Method A) to give dimethyl (4S,7S,10aS,4′S,7′S,10a′S)-4,4′-(((2R,5R)-2-benzyl-5-(cyanomethyl)-1,6-dioxo-1,6-hexanediyl)diimino)bis(5-oxooctahydro-7H-pyrido[2,1-b][1,3]thiazepine-7-carboxylate) (13 mg, 0.018 mmol, 51% yield). Anal. Calcd. for C37H49N5O8S2 m/z 755.7. found: 756.2 (M+H)+; 1H NMR (400 MHz, CDCl3) δ ppm 7.74 (1H, d, J=6.6 Hz), 7.30-7.21 (3H, m), 7.20-7.11 (3H, m), 5.44-5.35 (2H, m), 5.18-5.00 (4H, m), 3.72 (3H, s), 3.69 (3H, s), 3.20 (1H, ddd, J=14.0, 10.7, 2.7 Hz), 3.15-3.01 (3H, m), 2.96 (1H, ddd, J=14.4, 7.0, 2.7 Hz), 2.91-2.82 (2H, m), 2.71 (1H, dd, J=13.2, 6.6 Hz), 2.65-2.55 (2H, m), 2.53-2.35 (4H, m), 2.25 (1H, ddd, J=10.7, 6.9, 3.3 Hz), 2.09-1.96 (4H, m), 1.82 (1H, td, J=7.1, 3.8 Hz), 1.78-1.51 (10H, m).
