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Nitric Acid → 3-(5-Nitro-3-methyl-thiophene-2-yl)-7-(1-ethyl-propyl)-2,5-dimethyl-pyrazolo[1,5-a]pyrimidine

HRID 1639667
Notes
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Reaction equation

HRID 1639667 reaction equation
[CH3:1][C:2]1[CH:6]=[CH:5][S:4][C:3]=1[C:7]1[C:8]([CH3:22])=[N:9][N:10]2[C:15]([CH:16]([CH2:19][CH3:20])[CH2:17][CH3:18])=[CH:14][C:13]([CH3:21])=[N:12][C:11]=12.FC(F)(F)C(O)=O.[N+:30]([O-])([OH:32])=[O:31]>ClCCl>[N+:30]([C:5]1[S:4][C:3]([C:7]2[C:8]([CH3:22])=[N:9][N:10]3[C:15]([CH:16]([CH2:17][CH3:18])[CH2:19][CH3:20])=[CH:14][C:13]([CH3:21])=[N:12][C:11]=23)=[C:2]([CH3:1])[CH:6]=1)([O-:32])=[O:31]
ParticipantsConditionsProcedureWorkupSources & evidenceReaction notes

Participants

5

Reactant 3

HCID 944Nitric AcidHCID 6422Trifluoroacetic acidHCID 248987423-(3-Methyl-thiophene-2-yl)-7-(1-ethyl-propyl)-2,5-dimethyl-pyrazolo[1,5-a]pyrimidine

Product 1

HCID 667211283-(5-Nitro-3-methyl-thiophene-2-yl)-7-(1-ethyl-propyl)-2,5-dimethyl-pyrazolo[1,5-a]pyrimidineYield 76.1%

Reagents, catalysts & solvents 1

HCID 6344
Dichloromethane
Solvent
2×

Conditions

Temperature
0 °C

Procedure

Dissolve 3-(3-methyl-thiophene-2-yl)-7-(1-ethyl-propyl)-2,5-dimethyl-pyrazolo[1,5-a]pyrimidine (0.419 g, 1.33 mmol) in dichloromethane (2.5 mL), stir under an inert atmosphere, chill in an ice bath to 0° C. and add trifluoroacetic acid (5 mL). Add concentrated (70%) nitric acid (0.132 g, 1.47 mmol) to the reaction dropwise. The solution changes color from yellow to dark green. Stir 1 h under an inert atmosphere while in an ice bath and confirm the reaction is complete using TLC. Dilute the reaction with dichloromethane (80 mL) and quench with saturated sodium bicarbonate. Separate and extract the aqueous basic phase with dichloromethane (50 mL). Combine the organic phases, dry over anhydrous magnesium sulfate, filter, and concentrate under reduced pressure. Purify the resulting residue using flash chromatography, eluting with 100% hexane/0% (30% ethyl acetate/hexane) to 0% hexane/100% (30% ethyl acetate/hexane) in a step gradient of 10% increments to give a yellow solid (0.363 g, 76%). 1H NMR (400 MHz, CDCl3): δ 7.81 (s, 1H), 6.51 (s, 1H), 3.62-3.58 (m, 1H), 2.56 (s, 3H), 2.48 (s, 3H), 2.18 (s, 3H), 1.88-1.70 (m, 4H), 0.88 (t, J=7.5 Hz, 6H).

Workup

  1. additionAdd
  2. customto the reaction dropwise
  3. stirringStir 1 h under an inert atmosphere while in an ice bath
  4. additionDilute
  5. customquench with saturated sodium bicarbonate
  6. customSeparate
  7. extractionextract the aqueous basic phase with dichloromethane (50 mL)
  8. dry with materialCombine the organic phases, dry over anhydrous magnesium sulfate
  9. filtrationfilter
  10. concentrationconcentrate under reduced pressure
  11. customPurify the resulting residue
  12. washeluting with 100% hexane/0% (30% ethyl acetate/hexane) to 0% hexane/100% (30% ethyl acetate/hexane) in a step gradient of 10% increments

Sources & evidence

ORD record
ord-d6dc18cfa49b46d0869688297157e56b
Source dataset
uspto-grants-2012_02
DOI
10.6084/m9.figshare.5104873.v1
Patent number
US08110580B2

Reaction notes

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On this pageParticipantsConditionsProcedureWorkupSources & evidenceReaction notes