Sodium Carbonate → 2-(benzyloxy)-6,7-dihydropyrazolo[1,5-a]pyrazin-4(5H)-one

HRID 1396510Notes

Reaction equation

HRID 1396510 reaction equation
[CH2:1]([O:8][C:9]1[CH:13]=[C:12](C(OCC)=O)[N:11]([CH2:19][CH2:20][NH:21][C:22]([O:24]C(C)(C)C)=O)[N:10]=1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.C([O-])([O-])=O.[Na+].[Na+]>Cl.O1CCOCC1.O>[CH2:1]([O:8][C:9]1[CH:13]=[C:12]2[C:22](=[O:24])[NH:21][CH2:20][CH2:19][N:11]2[N:10]=1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1

Participants

6

Reactant 2

HCID 10340Sodium CarbonateHCID 86706489ethyl 3-(benzyloxy)-1-{2-[(tert-butoxycarbonyl)amino]ethyl}-1H-pyrazole-5-carboxylate

Product 1

HCID 727147872-(benzyloxy)-6,7-dihydropyrazolo[1,5-a]pyrazin-4(5H)-oneYield 99%

Reagents, catalysts & solvents 3

HCID 313Hydrochloric AcidSolventHCID 962WaterSolventHCID 312751,4-DioxaneSolvent

Procedure

Ethyl 3-(benzyloxy)-1-{2-[(tert-butoxycarbonyl)amino]ethyl}-1H-pyrazole-5-carboxylate (0.51 g, 1.31 mmol) was dissolved in a 4 M solution of HCl in 1,4-dioxane (6.53 mL). The mixture was stirred at room temperature for 1 hour and then made basic using a saturated solution of Na2CO3. The mixture was stirred at room temperature for 1 hour, diluted with water and extracted with DCM. The organic layer was separated, dried (Na2SO4), filtered and the solvents evaporated in vacuo. The crude product was purified by flash column chromatography (silica; 7 M solution of ammonia in MeOH in DCM 0/100 to 10/90). The desired fractions were collected and the solvents evaporated in vacuo to yield 2-(benzyloxy)-6,7-dihydropyrazolo[1,5-a]pyrazin-4(5H)-one (0.31 g, 99% yield) as a white solid. C13H13N3O2. 1H NMR (400 MHz, CDCl3) δ ppm 3.63-3.73 (m, 2H), 4.13 (dd, J=6.9, 5.4 Hz, 2H), 5.13 (s, 2H), 6.20 (s, 1H), 7.22 (br. s., 1H), 7.23-7.28 (m, 1H), 7.28-7.34 (m, 2H), 7.34-7.41 (m, 2H).

Workup

  1. stirringThe mixture was stirred at room temperature for 1 hour
  2. extractionextracted with DCM
  3. customThe organic layer was separated
  4. dry with materialdried (Na2SO4)
  5. filtrationfiltered
  6. customthe solvents evaporated in vacuo
  7. customThe crude product was purified by flash column chromatography (silica; 7 M solution of ammonia in MeOH in DCM 0/100 to 10/90)
  8. customThe desired fractions were collected
  9. customthe solvents evaporated in vacuo

Sources & evidence

ORD record
ord-43a5880769934af29a68ff4ab455dc9d
Source dataset
uspto-grants-2014_12
Patent number
US08901125B2

Reaction notes

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