Trifluoroacetic anhydride → 3-bromo-5H,6H,7H-cyclopenta(b)pyridin-7-ol

HRID 2046537Notes

Reaction equation

HRID 2046537 reaction equation
[Br:1][C:2]1[CH:3]=[N+:4]([O-])[C:5]2[CH2:6][CH2:7][CH2:8][C:9]=2[CH:10]=1.FC(F)(F)C(OC(=O)C(F)(F)F)=[O:15]>C(Cl)Cl>[Br:1][C:2]1[CH:3]=[N:4][C:5]2[CH:6]([OH:15])[CH2:7][CH2:8][C:9]=2[CH:10]=1

Participants

4

Reactant 2

HCID 9845Trifluoroacetic anhydrideHCID 115067543-Bromo-6,7-dihydro-5H-cyclopenta[b]pyridine 1-oxide

Product 1

HCID 468641543-bromo-5H,6H,7H-cyclopenta(b)pyridin-7-olYield 77.1%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Procedure

3-Bromo-6,7-dihydro-5H-[1]pyrindine 1-oxide (6.97 g, 32.6 mmol) was dissolved in CH2Cl2 (150 ml); then, trifluoroacetic anhydride (20.5 g, 13.6 ml, 97.7 mmol) was added drop by drop below 25° C. with intense stirring and stirring was continued for 6 hours at RT. The mixture was then quenched with aqueous 1M NaOH solution. The aqueous mixture was stirred for two hours and extracted three times with CH2Cl2/2-propanol 4:1. The organic layers were dried over MgSO4, filtered and concentrated in vacuo to give a crude product (6.279 g) which was purified by flash chromatography (silica gel, 50 g, 20% to 100% EtOAc in heptane) to yield the title compound (5.38 g, 77%) as light brown solid. MS: 214.0 (MH+, 1Br).

Workup

  1. stirringstirring
  2. customThe mixture was then quenched with aqueous 1M NaOH solution
  3. stirringThe aqueous mixture was stirred for two hours
  4. extractionextracted three times with CH2Cl2/2-propanol 4:1
  5. dry with materialThe organic layers were dried over MgSO4
  6. filtrationfiltered
  7. concentrationconcentrated in vacuo
  8. customto give a crude product (6.279 g) which
  9. customwas purified by flash chromatography (silica gel, 50 g, 20% to 100% EtOAc in heptane)

Sources & evidence

ORD record
ord-3933d0f045224212b7d3377fe045a55a
Source dataset
uspto-grants-2013_11
Patent number
US08592426B2

Reaction notes

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