Cesium carbonate → 7-tert-butyl 1-methyl 3-phenyl-5,6-dihydroimidazo[1,5-a]pyrazine-1,7(8H)-dicarboxylate

HRID 535923Notes

Reaction equation

HRID 535923 reaction equation
Br[C:2]1[N:6]2[CH2:7][CH2:8][N:9]([C:11]([O:13][C:14]([CH3:17])([CH3:16])[CH3:15])=[O:12])[CH2:10][C:5]2=[C:4]([C:18]([O:20][CH3:21])=[O:19])[N:3]=1.[C:22]1(B(O)O)[CH:27]=[CH:26][CH:25]=[CH:24][CH:23]=1.C(=O)([O-])[O-].[Cs+].[Cs+].C([O-])(O)=O.[Na+]>C1(C)C=CC=CC=1>[C:22]1([C:2]2[N:6]3[CH2:7][CH2:8][N:9]([C:11]([O:13][C:14]([CH3:17])([CH3:16])[CH3:15])=[O:12])[CH2:10][C:5]3=[C:4]([C:18]([O:20][CH3:21])=[O:19])[N:3]=2)[CH:27]=[CH:26][CH:25]=[CH:24][CH:23]=1

Participants

6

Reactant 4

HCID 10796Cesium carbonateHCID 66827Phenylboronic AcidHCID 516892Sodium BicarbonateHCID 576351407-(tert-Butyl) 1-methyl 3-bromo-5,6-dihydroimidazo[1,5-a]pyrazine-1,7(8H)-dicarboxylate

Product 1

HCID 576350867-tert-butyl 1-methyl 3-phenyl-5,6-dihydroimidazo[1,5-a]pyrazine-1,7(8H)-dicarboxylateYield 70%

Reagents, catalysts & solvents 1

HCID 1140TolueneSolvent

Conditions

Temperature
110 °C

Procedure

To a round-bottomed flask charged with Intermediate 1H (2 g, 5.55 mmol), phenyl boronic acid (2.07 g, 16.65 mmol), [Pd-(dppf)Cl2] (0.45 g, 10 mol %), and cesium carbonate (5.45 g, 16.65 mmol) was added toluene (anhydrous and de-gassed; 80 mL). The reaction mixture was heated to 110° C. while stirring under argon for 6 hours. After cooling to room temperature, saturated aqueous NaHCO3 solution was added and the mixture was extracted three times with ethyl acetate. The combined extracts were dried over anhydrous MgSO4, filtered and concentrated under reduced pressure to give the crude product. Purification by column chromatography (silica), eluting with ethyl acetate/hexane mixtures, provided Intermediate 3A as a white solid (70% yield). 1H-NMR (400 MHz, CDCl3) δ: 1.52 (s, 9H), 3.79 (m, 2H), 3.93 (s, 3H), 4.12 (m, 2H), 5.00 (s, 2H), 7.43-7.47 (m, 3H), 7.63-7.66 (m, 2H). LCMS (+ESI) m/z 358.28 [M+H]+.

Workup

  1. temperatureAfter cooling to room temperature
  2. extractionthe mixture was extracted three times with ethyl acetate
  3. dry with materialThe combined extracts were dried over anhydrous MgSO4
  4. filtrationfiltered
  5. concentrationconcentrated under reduced pressure
  6. customto give the crude product
  7. customPurification by column chromatography (silica)
  8. washeluting with ethyl acetate/hexane mixtures

Sources & evidence

ORD record
ord-2c1d26620d034527b316d37bbddea0d3
Source dataset
uspto-grants-2014_10
Patent number
US08859538B2

Reaction notes

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