Water → 7-Chloro-2-(4-methoxyphenyl)pyrazolo[1,5-A]pyridine

HRID 861104Notes

Reaction equation

HRID 861104 reaction equation
[Cl:1][C:2]1[N:7]=[C:6]([CH2:8][C:9]([C:12]2[CH:17]=[CH:16][C:15]([O:18][CH3:19])=[CH:14][CH:13]=2)=[N:10]O)[CH:5]=[CH:4][CH:3]=1.FC(F)(F)C(OC(=O)C(F)(F)F)=O.C(N(CC)CC)C.O>COCCOC.[Fe](Cl)Cl>[Cl:1][C:2]1[N:7]2[N:10]=[C:9]([C:12]3[CH:17]=[CH:16][C:15]([O:18][CH3:19])=[CH:14][CH:13]=3)[CH:8]=[C:6]2[CH:5]=[CH:4][CH:3]=1

Participants

7

Reactant 4

HCID 962WaterHCID 8471TriethylamineHCID 9845Trifluoroacetic anhydrideHCID 738583202-(6-Chloro-2-pyridinyl)-1-(4-methoxyphenyl)ethanone oxime

Product 1

HCID 223500457-Chloro-2-(4-methoxyphenyl)pyrazolo[1,5-A]pyridineYield 52%

Reagents, catalysts & solvents 2

HCID 24458Ferrous ChlorideCatalystHCID 80711,2-DimethoxyethaneSolvent2×

Conditions

Temperature
15 °C

Procedure

To a solution of 2-(6-chloro-2-pyridinyl)-1-(4-methoxyphenyl)ethanone oxime (38.7 g, 140 mmol) in 1,2-dimethoxyethane (150 mL) at 0° C. was added trifluoroacetic anhydride (20 mL, 140 mmol), keeping the temperature below 10° C. during the addition. After the addition was complete, the reaction was warmed to 15° C. The solution was then cooled to 4° C. and a solution of triethylamine (39 mL, 280 mmol) in 1,2-dimethoxyethane (15 mL) was added over a period of 0.5 hours. The mixture was allowed to warm to room temperature and was stirred at room temperature for 1.5 hours. To this mixture was added iron(II) chloride (0.18 g, 1.4 mmol) and the reaction was heated at 75° C. for 15 hours. The reaction mixture was poured into water (300 mL). The resulting suspension was extracted with ethyl acetate. The organic phase was dried (magnesium sulfate), filtered and concentrated to a solid. This solid was recrystallized from methanol to give 7-chloro-2-(4-methoxyphenyl)pyrazolo[1,5-a]pyridine (18.7 g, 52%) as pale yellow needles. 1H NMR (CDCl3): δ 7.91 (d, 2H), 7.43 (d, 1H), 7.01 (t,1H), 6.95 (d, 2H), 6.81 (d, 1H), 6.80 (s, 1H), 3.83 (s, 3H); MS m/z 259 (M+1).

Workup

  1. customthe temperature below 10° C.
  2. additionduring the addition
  3. additionAfter the addition
  4. temperatureThe solution was then cooled to 4° C.
  5. temperatureto warm to room temperature
  6. temperaturethe reaction was heated at 75° C. for 15 hours
  7. extractionThe resulting suspension was extracted with ethyl acetate
  8. dry with materialThe organic phase was dried (magnesium sulfate)
  9. filtrationfiltered
  10. concentrationconcentrated to a solid
  11. customThis solid was recrystallized from methanol

Sources & evidence

ORD record
ord-51191a1c4e8d4b1b87bce5a1d24ac385
Source dataset
uspto-grants-2006_12
Patent number
US07153855B2

Reaction notes

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