Tert-butyl 4-methyl-2-(4-nitrophenyl)-3-oxopiperazine-1-carboxylate → Tert-butyl 2-(4-aminophenyl)-4-methyl-3-oxopiperazine-1-carboxylate

HRID 1772079Notes

Reaction equation

HRID 1772079 reaction equation
[CH3:1][N:2]1[CH2:7][CH2:6][N:5]([C:8]([O:10][C:11]([CH3:14])([CH3:13])[CH3:12])=[O:9])[CH:4]([C:15]2[CH:20]=[CH:19][C:18]([N+:21]([O-])=O)=[CH:17][CH:16]=2)[C:3]1=[O:24]>C(O)C>[NH2:21][C:18]1[CH:19]=[CH:20][C:15]([CH:4]2[C:3](=[O:24])[N:2]([CH3:1])[CH2:7][CH2:6][N:5]2[C:8]([O:10][C:11]([CH3:14])([CH3:13])[CH3:12])=[O:9])=[CH:16][CH:17]=1

Participants

3

Reactant 1

HCID 66634719Tert-butyl 4-methyl-2-(4-nitrophenyl)-3-oxopiperazine-1-carboxylate

Product 1

HCID 66634693Tert-butyl 2-(4-aminophenyl)-4-methyl-3-oxopiperazine-1-carboxylateYield 99%

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

Procedure

A 250-mL Parr hydrogenation bottle was purged with nitrogen and charged with 10% palladium on carbon (50% wet, 10 mg dry weight) followed by a solution of tert-butyl 4-methyl-2-(4-nitrophenyl)-3-oxopiperazine-1-carboxylate (102i) (1.00 g, 2.99 mmol) in ethanol (40 mL). The bottle was evacuated, then charged with hydrogen gas to a pressure of 50 psi and shaken at 50 psi for 18 h at room temperature on a Parr hydrogenation apparatus. After this time the hydrogen was evacuated and nitrogen charged into the bottle. The resulting suspension was filtered through a pad of Celite 521. The filter cake was washed with ethanol (2×20 mL), and the filtrate was evaporated to dryness under reduced pressure to afford a 99% yield (904 mg) of tert-butyl 2-(4-aminophenyl)-4-methyl-3-oxopiperazine-1-carboxylate 102j as a yellow syrup: 1H NMR (300 MHz, DMSO-d6) δ 6.93 (d, 2H, J=8.4 Hz), 6.51 (d, 2H, J=8.4 Hz), 5.27 (bs, 1H), 5.09 (s, 1H), 3.83 (d, 1H, J=10.8 Hz), 3.44 (m, 1H), 3.24 (m, 2H), 2.84 (s, 3H), 1.40 (s, 9H); MS (ESI+) m/z 306.2 (M+H).

Workup

  1. customA 250-mL Parr hydrogenation bottle was purged with nitrogen
  2. additioncharged with 10% palladium on carbon (50% wet, 10 mg dry weight)
  3. customThe bottle was evacuated
  4. additioncharged with hydrogen gas to a pressure of 50 psi
  5. customAfter this time the hydrogen was evacuated
  6. additionnitrogen charged into the bottle
  7. filtrationThe resulting suspension was filtered through a pad of Celite 521
  8. washThe filter cake was washed with ethanol (2×20 mL)
  9. customthe filtrate was evaporated to dryness under reduced pressure

Sources & evidence

ORD record
ord-5b0334ff657b462ba79ed2366167eee0
Source dataset
uspto-grants-2016_02
Patent number
US09249123B2

Reaction notes

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