Cesium carbonate → tert-butyl (3R)-3-methyl-4-(6-nitro-3-pyridyl)piperazine-1-carboxylate

HRID 1843216Notes

Reaction equation

HRID 1843216 reaction equation
Br[C:2]1[CH:3]=[CH:4][C:5]([N+:8]([O-:10])=[O:9])=[N:6][CH:7]=1.[CH3:11][C@H:12]1[NH:17][CH2:16][CH2:15][N:14]([C:18]([O:20][C:21]([CH3:24])([CH3:23])[CH3:22])=[O:19])[CH2:13]1.C(=O)([O-])[O-].[Cs+].[Cs+].CC1(C)C2C(=C(P(C3C=CC=CC=3)C3C=CC=CC=3)C=CC=2)OC2C(P(C3C=CC=CC=3)C3C=CC=CC=3)=CC=CC1=2>C1C=CC(/C=C/C(/C=C/C2C=CC=CC=2)=O)=CC=1.C1C=CC(/C=C/C(/C=C/C2C=CC=CC=2)=O)=CC=1.C1C=CC(/C=C/C(/C=C/C2C=CC=CC=2)=O)=CC=1.[Pd].[Pd].O1CCOCC1>[CH3:11][C@H:12]1[N:17]([C:2]2[CH:7]=[N:6][C:5]([N+:8]([O-:10])=[O:9])=[CH:4][CH:3]=2)[CH2:16][CH2:15][N:14]([C:18]([O:20][C:21]([CH3:22])([CH3:24])[CH3:23])=[O:19])[CH2:13]1

Participants

7

Reactant 4

HCID 10796Cesium carbonateHCID 6360441,1'-(9,9-Dimethyl-9H-xanthene-4,5-diyl)bis(1,1-diphenylphosphine)HCID 8176205-Bromo-2-nitropyridineHCID 2756811(R)-1-Boc-3-methylpiperazine

Product 1

HCID 86683716tert-butyl (3R)-3-methyl-4-(6-nitro-3-pyridyl)piperazine-1-carboxylateYield 49.6%

Reagents, catalysts & solvents 2

HCID 9811564Bis(dibenzylideneacetone)palladiumCatalystHCID 312751,4-DioxaneSolvent

Conditions

Temperature
100 °C

Procedure

A 250-mL single-neck round-bottomed flask equipped with a magnetic stirrer and a reflux condenser was charged with 1,4-dioxane (60 mL), 5-bromo-2-nitropyridine (2.0 g, 10.0 mmol), (R)-tert-butyl 3-methylpiperazine-1-carboxylate (2.0 g, 10.0 mmol), and cesium carbonate (6.5 g, 20 mmol). After bubbling nitrogen through the resulting mixture for 10 minutes, tris(dibenzylideneacetone)dipalladium(0) (915 mg, 1.0 mmol) and XantPhos (579 mg, 1.0 mmol) were added. The system was subjected to three cycles of vacuum/argon flush and heated at 100° C. for 15 h. After this time the reaction was cooled to room temperature and filtered. The filtrate was partitioned between ethyl acetate (100 mL) and water (100 mL). The aqueous layer was separated and extracted with ethyl acetate (3×50 mL). The combined organic layer was washed with brine (100 mL) and dried over sodium sulfate. The drying agent was removed by filtration and the filtrate was concentrated under reduced pressure. The residue was purified by silica-gel column chromatography eluting with 30:1 dichloromethane/methanol to afford 115a (1.6 g, 44%) as a yellow solid. MS-ESI: [M+H]+ 323. 1H NMR (500 MHz, DMSO-d6) δ 8.21 (d, J=3.5 Hz, 1H), 8.18 (d, J=9.0 Hz, 1H), 7.45-7.43 (m, 1H), 4.34-4.33 (m, 1H), 3.92-3.99 (m, 1H), 3.80 (d, J=12.5 Hz, 2H), 3.06-3.23 (m, 3H), 1.43 (s, 9H), 1.09 (d, J=6.5 Hz, 3H).

Workup

  1. customA 250-mL single-neck round-bottomed flask equipped with a magnetic stirrer and a reflux condenser
  2. customAfter bubbling nitrogen through the resulting mixture for 10 minutes
  3. customflush
  4. temperatureAfter this time the reaction was cooled to room temperature
  5. filtrationfiltered
  6. customThe filtrate was partitioned between ethyl acetate (100 mL) and water (100 mL)
  7. customThe aqueous layer was separated
  8. extractionextracted with ethyl acetate (3×50 mL)
  9. washThe combined organic layer was washed with brine (100 mL)
  10. dry with materialdried over sodium sulfate
  11. customThe drying agent was removed by filtration
  12. concentrationthe filtrate was concentrated under reduced pressure
  13. customThe residue was purified by silica-gel column chromatography
  14. washeluting with 30:1 dichloromethane/methanol

Sources & evidence

ORD record
ord-f75f04f03f2544d983095538532c1d28
Source dataset
uspto-grants-2015_02
Patent number
US08946213B2

Reaction notes

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