Potassium Carbonate → tert-Butyl 8-bromo-3,4-dihydropyrazino[1,2-a]benzimidazole-2(1H)-carboxylate

HRID 882061Notes

Reaction equation

HRID 882061 reaction equation
CS(O[CH2:6][CH2:7][N:8]1[C:12]2[CH:13]=[CH:14][C:15]([Br:17])=[CH:16][C:11]=2[N:10]=[C:9]1[CH2:18][NH:19][C:20]([O:22][C:23]([CH3:26])([CH3:25])[CH3:24])=[O:21])(=O)=O.O.CC(O)C.C([O-])([O-])=O.[K+].[K+].C(OC(OC(C)(C)C)=O)(OC(C)(C)C)=O>C(O)(C(F)(F)F)=O.O>[Br:17][C:15]1[CH:14]=[CH:13][C:12]2[N:8]3[CH2:7][CH2:6][N:19]([C:20]([O:22][C:23]([CH3:26])([CH3:25])[CH3:24])=[O:21])[CH2:18][C:9]3=[N:10][C:11]=2[CH:16]=1

Participants

7

Reactant 4

HCID 11430Potassium CarbonateHCID 90495Di-tert-butyl dicarbonateHCID 21889133Propan-2-ol--water (1/1)HCID 575147692-(5-Bromo-2-((tert-butoxycarbonylamino)methyl)-1H-benzo[d]imidazol-1-yl)ethyl methanesulfonate

Product 1

HCID 67988850tert-Butyl 8-bromo-3,4-dihydropyrazino[1,2-a]benzimidazole-2(1H)-carboxylateYield 89%

Reagents, catalysts & solvents 2

HCID 962WaterSolventHCID 6422Trifluoroacetic acidSolvent

Conditions

Temperature
105 °C

Procedure

2-(5-Bromo-2-((tert-butoxycarbonylamino)methyl)-1H-benzo[d]imidazol-1-yl)ethyl methanesulfonate (883 mg, crude, 1.76 mmol estimated) was stirred in TFA (10 mL) for 1 h and then concentrated. Water/i-PrOH (32 mL/8 mL) and K2CO3 (2.31 g, 16.7 mmol) were added, and the mixture was heated at 105° C. for 2 h and then cooled to room temperature. Di-tert-butyl dicarbonate (812 mg, 3.73 mmol) was added, and the reaction mixture was stirred for 48 h and then diluted with water. The solid was filtered off and dried under vacuum to provide the title compound (549 mg, 89%) as a brown solid: ESI MS m/z 352 [M+H]+.

Workup

  1. concentrationconcentrated
  2. temperaturecooled to room temperature
  3. filtrationThe solid was filtered off
  4. customdried under vacuum

Sources & evidence

ORD record
ord-d7a0e395fa5349f2b809b292657c77a3
Source dataset
uspto-grants-2015_03
Patent number
US08993765B2

Reaction notes

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