(R)-tert-butyl 2-isopropyl-4-(4-(methoxycarbonyl)-5-(methylsulfonyl)-2-nitrophenyl)-3-oxopiperazine-1-carboxylate → (R)-tert-butyl 4-(2-amino-4-(methoxycarbonyl)-5-(methylsulfonyl)phenyl)-2-isopropyl-3-oxopiperazine-1-carboxylate

Participants

Reaction Steps

To a 1 L round-bottom flask containing (R)-tert-butyl 2-isopropyl-4-(4-(methoxycarbonyl)-5-(methylsulfonyl)-2-nitrophenyl)-3-oxopiperazine-1-carboxylate (26.3 g, 0.0526 mol) in THF (200 mL) and methanol (200 mL) was added Raney Nickel (in H2O, 4 g). The mixture was stirred under H2 (30 psi) at rt overnight. The mixture was filtered and concentrated under vacuum to give (R)-tert-butyl 4-(2-amino-4-(methoxycarbonyl)-5-(methylsulfonyl)phenyl)-2-isopropyl-3-oxopiperazine-1-carboxylate (24.7 g, 100% yield) as a yellow solid. The residue was used directly for the next step without further purification. LC-MS MS (ESI) m/z 414.0 [M−56+H]+, 492.0 [M+Na]+. 1H NMR (CDCl3 300 MHz): δ 7.77 (brs, 1H), 7.04 (s, 1H), 4.68-4.45 (m, 1H), 4.45-4.38 (m, 2H), 3.92 (s, 3H), 3.70-3.58 (m, 1H), 3.58-3.41 (m, 1H), 3.30 (s, 3H), 2.49-2.25 (m, 1H), 1.50 (s, 9H), 1.12 (d, J=6.9 Hz, 3H), 1.05 (d, J=6.9 Hz, 3H).

Provenance & Evidence