Trifluoroacetic acid → N-[2-({4-[4-(3-Bromo-4-fluorophenyl)-5-oxo-4,5-dihydro-1,2,4-oxadiazol-3-yl]-1,2,5-oxadiazol-3-yl}amino)ethyl]sulfamide

Participants

Reaction Steps

To a 22 L flask containing 98:2 trifluoroacetic acid:water (8.9 L) was added tert-butyl ({[2-({4-[4-(3-bromo-4-fluorophenyl)-5-oxo-4,5-dihydro-1,2,4-oxadiazol-3-yl]-1,2,5-oxadiazol-3-yl}amino)ethyl]amino}sulfonyl)carbamate (1931 g, 3.42 mol) in portions over 10 minutes. The resulting mixture was stirred at room temperature for 1.5 h, the solvents removed in vacuo, and chased with dichloromethane (2 L). The resulting solid was treated a second time with fresh 98:2 trifluoroacetic acid:water (8.9 L), heated for 1 h at 40-50° C., the solvents removed in vacuo, and chased with dichloromethane (3×2 L). The resulting white solid was dried in a vacuum drying oven at 50° C. overnight. A total of 5409 g was processed in this manner (4990 g, quant. yield). LCMS for C12H12BrFN7O5S (M+H)+: m/z=463.9, 465.9. 1H NMR (400 MHz, DMSO-d6): δ 8.08 (dd, J=6.2, 2.5 Hz, 1 H), 7.72 (m, 1 H), 7.59 (t, J=8.7 Hz, 1 H), 6.67 (t, J=5.9 Hz, 1 H), 6.52 (t, J=6.0 Hz, 1 H), 3.38 (dd, J=12.7, 6.3 Hz, 2 H), 3.11 (dd, J=12.3, 6.3 Hz).

Provenance & Evidence