2,6-Diamino-3-nitropyridine → 3-Phenylpyrido[2,3-b]pyrazin-6-ylamine

HRID 215796

Reaction equation

HRID 215796 reaction equation
[NH2:1][C:2]1[C:7]([N+:8]([O-])=O)=[CH:6][CH:5]=[C:4]([NH2:11])[N:3]=1.O.[C:13]1([C:19]([CH:21]=O)=O)[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1>C(O)C.[Ni]>[C:13]1([C:19]2[N:1]=[C:2]3[N:3]=[C:4]([NH2:11])[CH:5]=[CH:6][C:7]3=[N:8][CH:21]=2)[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=1

Participants

5

Reactant 2

HCID 3199982,6-Diamino-3-nitropyridineHCID 12215922Glyoxal, phenyl-, hydrate

Product 1

HCID 121331983-Phenylpyrido[2,3-b]pyrazin-6-ylamine

Reagents, catalysts & solvents 2

HCID 935NickelCatalystHCID 702EthanolSolvent2×

Procedure

A solution of 1.22 g of 2,6-diamino-3-nitropyridine (7.92 mmol) in 210 ml of ethanol is hydrogenated with Raney nickel as catalyst at 50° C. and 5 bar. After the hydrogenation is complete, the catalyst is filtered off with suction through a glass fibre filter. Before the filtration, 1.68 g of phenylglyoxal hydrate (11.03 mmol) are introduced into 50 ml of ethanol in the receiver. The catalyst is then filtered off under nitrogen as protective gas, and the hydrogenation solution is sucked directly into the reaction flask. The greenish blue reaction mixture is heated under reflux under nitrogen for 30 min. The mixture is allowed to cool, and the solvent is removed in vacuo. A dark brown solid is finally obtained. Purification by column chromatography on silica gel (mobile phase dichloromethane/methanol mixture) affords a pale yellow crystalline solid.

Workup

  1. filtrationthe catalyst is filtered off with suction through a glass fibre filter
  2. filtrationThe catalyst is then filtered off under nitrogen as protective gas
  3. customThe greenish blue reaction mixture
  4. temperatureis heated
  5. temperatureunder reflux under nitrogen for 30 min
  6. temperatureto cool
  7. customthe solvent is removed in vacuo
  8. customA dark brown solid is finally obtained
  9. customPurification by column chromatography on silica gel (mobile phase dichloromethane/methanol mixture)
  10. customaffords a pale yellow crystalline solid

Sources & evidence

ORD record
ord-c099f283504f477e828fc227eb9fd20b
Source dataset
uspto-grants-2012_06
Patent number
US08193186B2

Linked notes

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