Hydrogen Bromide → 5,8-Dibromoimidazo[1,2-a]pyrazine

HRID 1921735Notes

Reaction equation

HRID 1921735 reaction equation
C(O[CH:4](OCC)[CH2:5][Br:6])C.Br.[Br:11][C:12]1[C:17]([NH2:18])=[N:16][C:15](Br)=[CH:14][N:13]=1>CC(O)C>[Br:11][C:12]1[N:13]2[CH:14]=[CH:15][N:16]=[C:4]2[C:5]([Br:6])=[N:18][CH:17]=1

Participants

5

Reactant 3

HCID 260Hydrogen BromideHCID 74852Ethane, 2-bromo-1,1-diethoxy-HCID 510516652-Amino-3,6-dibromopyrazine

Product 1

HCID 534859495,8-Dibromoimidazo[1,2-a]pyrazine

Reagents, catalysts & solvents 1

HCID 3776IsopropanolSolvent

Procedure

Bromoacetaldehyde diethyl acetal (49 mL, 326 mmol) and 48% hydrobromic acid is heated to reflux for 1.5 h, then poured into propan-2-ol (600 mL) and quenched with NaHCO3. After filtering, 2,5-dibromo-3-aminopyrazine (41.34 g, 163 mmol) is added to the solution and heated at reflux overnight. The reaction is cooled and solvents removed in vacuo, followed by addition of aq. NaHCO3 and extraction with EtOAc. The organic phase is dried over MgSO4, filtered, and concentrated in vacuo to afford a brown solid. 1H NMR (250 MHz, CDCl3) δ(ppm) 7.86 (1H, s), 7.93-7.94 (1H, d), 7.98-7.99 (1H, d); m/z (APCI) 278 (M+H)+; m.p 132-135° C.

Workup

  1. temperatureto reflux for 1.5 h
  2. customquenched with NaHCO3
  3. filtrationAfter filtering
  4. temperatureheated
  5. temperatureat reflux overnight
  6. temperatureThe reaction is cooled
  7. customsolvents removed in vacuo
  8. additionfollowed by addition of aq. NaHCO3 and extraction with EtOAc
  9. dry with materialThe organic phase is dried over MgSO4
  10. filtrationfiltered
  11. concentrationconcentrated in vacuo
  12. customto afford a brown solid
  13. customm.p 132-135° C.

Sources & evidence

ORD record
ord-db183110874348a6b98ba57d92a995b8
Source dataset
uspto-grants-2012_05
Patent number
US08173656B2

Reaction notes

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