Lithium Chloride → 2-Ethyl-3-(4-pyridyl)-imidazo[1,2-a]pyridine

HRID 1068231Notes

Reaction equation

HRID 1068231 reaction equation
Br[C:2]1[N:6]2[CH:7]=[CH:8][CH:9]=[CH:10][C:5]2=[N:4][C:3]=1[CH2:11][CH3:12].C([Sn](CCCC)(CCCC)[C:18]1[CH:23]=[CH:22][N:21]=[CH:20][CH:19]=1)CCC.[Li+].[Cl-]>C1(C)C=CC=CC=1.[Pd]>[CH2:11]([C:3]1[N:4]=[C:5]2[CH:10]=[CH:9][CH:8]=[CH:7][N:6]2[C:2]=1[C:18]1[CH:23]=[CH:22][N:21]=[CH:20][CH:19]=1)[CH3:12]

Participants

6

Reactant 3

HCID 433294Lithium ChlorideHCID 27373184-(Tri-n-butylstannyl)pyridineHCID 219127413-Bromo-2-ethyl-imidazo[1,2-a]pyridine

Product 1

HCID 219127892-Ethyl-3-(4-pyridyl)-imidazo[1,2-a]pyridineYield 38.7%

Reagents, catalysts & solvents 2

HCID 23938PalladiumCatalystHCID 1140TolueneSolvent

Procedure

To a solution of 3-bromo-2-ethyl-imidazo[1,2-a]pyridine (1.4 g, 6.28 mmol), 4-tributylstannylpyridine (2.31 g, 6.28 mmol) and Pd (II) (Ph3P)2Cl2 (442 mg, 0.63 mmol) in toluene (5 mL) was added LiCl (26.7 mg, 0.63). After refluxing for 18 h, the mixture was partitioned between EtOAc and aqueous NaHCO3. The aqueous layer was extracted with EtOAc (3×). Combined organic phase was washed with brine and dried over anhydrous MgSO4. Concentration followed by flash chromatography eluting with 100% EtOAc, then 10% MeOH in CH2Cl2 afforded the title compound (543 mg) as a viscous oil. 1H NMR (500 MHz, CDCl3): δ 1.36 (t, J=7.5 Hz, 3H), 2.84 (q, J=7.5 Hz, 2H), 6.68 (dt, J=6.8, 1.1 Hz, 1H), 7.21 (m, 1H), 7.39 (dd, J=5.9, 1.6 Hz, 2H), 7.61 (dd, J=8.9, 1.0 Hz, 1H), 8.75 (d, J=5.9 Hz, 2H).

Workup

  1. temperatureAfter refluxing for 18 h
  2. customthe mixture was partitioned between EtOAc and aqueous NaHCO3
  3. extractionThe aqueous layer was extracted with EtOAc (3×)
  4. washCombined organic phase was washed with brine
  5. dry with materialdried over anhydrous MgSO4
  6. concentrationConcentration
  7. washeluting with 100% EtOAc

Sources & evidence

ORD record
ord-b5a748f8ba6a4881905b534cf7e1f8f7
Source dataset
uspto-grants-2001_06
Patent number
US06248755B1

Reaction notes

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