Acetaldehyde → 5-Ethyl-2-nitro-4,5,6,7-tetrahydropyrazolo[1,5-a]pyrazine

HRID 1021944Notes

Reaction equation

HRID 1021944 reaction equation
[N+:1]([C:4]1[CH:12]=[C:7]2[CH2:8][NH:9][CH2:10][CH2:11][N:6]2[N:5]=1)([O-:3])=[O:2].[CH:13](=O)[CH3:14].[BH3-]C#N.[Na+]>[Cl-].[Cl-].[Zn+2].CO>[CH2:13]([N:9]1[CH2:10][CH2:11][N:6]2[N:5]=[C:4]([N+:1]([O-:3])=[O:2])[CH:12]=[C:7]2[CH2:8]1)[CH3:14]

Participants

6

Reactant 3

HCID 177AcetaldehydeHCID 5003444Sodium cyanoborohydrideHCID 580442792-Nitro-4,5,6,7-tetrahydropyrazolo[1,5-a]pyrazine

Product 1

HCID 580439255-Ethyl-2-nitro-4,5,6,7-tetrahydropyrazolo[1,5-a]pyrazineYield 81%

Reagents, catalysts & solvents 2

HCID 3007855ZincchlorideCatalystHCID 887MethanolSolvent

Procedure

A 150-mL single-neck round-bottomed flask equipped with a magnetic stirrer was charged with methanol (60 mL), 2-nitro-4,5,6,7-tetrahydropyrazolo[1,5-a]pyrazine 205a (1.5 g, 8.9 mmol), ZnCl2 (2.43 g, 17.8 mmol), acetaldehyde (784 mg, 17.8 mmol), and NaBH3CN (1.12 g, 17.8 mmol). The mixture was stirred at room temperature for 2 h and concentrated under reduced pressure. The residue was purified with silica-gel column chromatography eluting with 40:1 petroleum ether/ethyl acetate to afford 208a (1.4 g, 81%) as a yellow oil. MS-ESI: [M+H]+ 197

Workup

  1. customA 150-mL single-neck round-bottomed flask equipped with a magnetic stirrer
  2. concentrationconcentrated under reduced pressure
  3. customThe residue was purified with silica-gel column chromatography
  4. washeluting with 40:1 petroleum ether/ethyl acetate

Sources & evidence

ORD record
ord-72a4f22b232c412f810f03c5cad21796
Source dataset
uspto-grants-2014_05
Patent number
US08716274B2

Reaction notes

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