Trifluoroacetic acid → 4-Chloro-2-isobutylimidazo[1,2-a]quinoxaline

HRID 1920955

Reaction equation

HRID 1920955 reaction equation
[Cl:1][C:2]1[C:3]([NH:12][CH:13]([CH2:16][CH:17]([CH3:19])[CH3:18])[CH:14]=O)=[N:4][C:5]2[C:10]([N:11]=1)=[CH:9][CH:8]=[CH:7][CH:6]=2.FC(F)(F)C(O)=O>FC(F)(F)C(OC(=O)C(F)(F)F)=O>[Cl:1][C:2]1[C:3]2[N:4]([CH:14]=[C:13]([CH2:16][CH:17]([CH3:19])[CH3:18])[N:12]=2)[C:5]2[C:10]([N:11]=1)=[CH:9][CH:8]=[CH:7][CH:6]=2

Participants

4

Reactant 2

HCID 6422Trifluoroacetic acidHCID 574259082-(3-Chloroquinoxalin-2-ylamino)-4-methylpentanal

Product 1

HCID 574259094-Chloro-2-isobutylimidazo[1,2-a]quinoxalineYield 65.4%

Reagents, catalysts & solvents 1

HCID 9845Trifluoroacetic anhydrideSolvent

Procedure

To a solution of the 2-(3-chloroquinoxalin-2-ylamino)-4-methylpentanal (1.03 g, 3.71 mmol) in 8 mL of trifluoroacetic anhydride was added 0.2 mL trifluoroacetic acid at room temperature. The reaction mixture was stirred at that temperature overnight. The solvents were removed under reduced pressure. And then 20 mL of saturated aqueous sodium bicarbonate was added. The resulting mixture was extracted with ethyl acetate (50 mL×3). The combined organic layers were washed with water (20 mL), brine (20 mL), dried over MgSO4, filtered and concentrated. The crude product was purified by flash column chromatography eluted with ethyl acetate and hexanes to give the titled compound (630 mg, 65%). MS: MH+=260:262=3:1. 1H NMR (300 MHz, CDCl3): δ 8.05 (m, 1H), 7.93 (s, 1H), 7.86 (m, 1H), 7.67 (m, 1H), 7.59 (m, 1H), 2.87 (d, 2H), 2.17 (m, 1H), 1.02 (d, 6H).

Workup

  1. customThe solvents were removed under reduced pressure
  2. additionAnd then 20 mL of saturated aqueous sodium bicarbonate was added
  3. extractionThe resulting mixture was extracted with ethyl acetate (50 mL×3)
  4. washThe combined organic layers were washed with water (20 mL), brine (20 mL)
  5. dry with materialdried over MgSO4
  6. filtrationfiltered
  7. concentrationconcentrated
  8. customThe crude product was purified by flash column chromatography
  9. washeluted with ethyl acetate and hexanes

Sources & evidence

ORD record
ord-6988a7e154e7418daa6046f35da0748e
Source dataset
uspto-grants-2012_05
Patent number
US08173657B2

Linked notes

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