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

HRID 1245570Notes

Reaction equation

HRID 1245570 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.[Cl-].[Li+]>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]pyridine

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 lithium chloride (26.7 mg, 0.63). After refluxing for 18 h, the mixture was partitioned between ethyl acetate and aqueous sodium bicarbonate. The aqueous layer was extracted with ethyl acetate (3×). Combined organic phase was washed with brine and dried over anhydrous magnesium sulfate. Concentration followed by flash chromatography eluting with 100% ethyl acetate, then 10% methanol in methylene chloride afforded the title compound 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 ethyl acetate and aqueous sodium bicarbonate
  3. extractionThe aqueous layer was extracted with ethyl acetate (3×)
  4. washCombined organic phase was washed with brine
  5. dry with materialdried over anhydrous magnesium sulfate
  6. concentrationConcentration
  7. washeluting with 100% ethyl acetate

Sources & evidence

ORD record
ord-7c6b951a0171476aa68ab7c33eab5782
Source dataset
uspto-grants-2006_10
Patent number
US07125887B2

Reaction notes

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