Potassium Carbonate → ethyl 3-methylquinoxaline-2-carboxylate

HRID 869674Notes

Reaction equation

HRID 869674 reaction equation
Cl[C:2]1[C:3]([C:12]([O-:14])=[O:13])=[N:4][C:5]2[C:10]([N:11]=1)=[CH:9][CH:8]=[CH:7][CH:6]=2.CB1OB(C)OB(C)O1.[C:24](=O)([O-])[O-].[K+].[K+].O1CCO[CH2:32][CH2:31]1>C(OCC)(=O)C.C1C=CC(P(C2C=CC=CC=2)[C-]2C=CC=C2)=CC=1.C1C=CC(P(C2C=CC=CC=2)[C-]2C=CC=C2)=CC=1.Cl[Pd]Cl.[Fe+2]>[CH3:24][C:2]1[C:3]([C:12]([O:14][CH2:31][CH3:32])=[O:13])=[N:4][C:5]2[C:10]([N:11]=1)=[CH:9][CH:8]=[CH:7][CH:6]=2

Participants

7

Reactant 4

HCID 11430Potassium CarbonateHCID 312751,4-DioxaneHCID 574072Trimethylboroxine2×HCID 28063031HCID 28063031, compound

Product 1

HCID 589024ethyl 3-methylquinoxaline-2-carboxylate

Reagents, catalysts & solvents 2

HCID 178418228Bis(cyclopenta-1,4-dien-1-yl(diphenyl)phosphane);dichloropalladium;iron(2+)CatalystHCID 8857Ethyl AcetateSolvent

Conditions

Temperature
115 °C

Procedure

A suspension of 3-chloroquinoxaline-2-carboxylate (86.0 g, 363 mmol), trimethylboroxine (22.8 g, 0.182 mmol), [1,1′-bis(diphenylphosphino)ferrocene]dichloropalladium(II) (8.90 g, 11.0 mmol), and potassium carbonate (100 g, 727 mmol) in 1,4-dioxane (726 mL) was heated at 115° C. for 4 h. And then trimethylboroxine (22.8 g, 0.182 mmol) was added again and heated at same temperature for 2 h. After being cooled to ambient temperature, the reaction mixture was diluted with ethyl acetate (700 mL) and filtrated through celite with ethyl acetate (1000 mL). The filtrate was combined and concentrated in vacuo. The residue was purified by silica gel column chromatography (silica gel 900 g, hexane:ethyl acetate=9:1 to 17:3) followed by recrystallization from cold hexane to give ethyl 3-methylquinoxaline-2-carboxylate. MS (APCI): m/z 217 (M+H).

Workup

  1. temperatureheated at same temperature for 2 h
  2. temperatureAfter being cooled to ambient temperature
  3. filtrationfiltrated through celite with ethyl acetate (1000 mL)
  4. concentrationconcentrated in vacuo
  5. customThe residue was purified by silica gel column chromatography (silica gel 900 g, hexane:ethyl acetate=9:1 to 17:3)
  6. customfollowed by recrystallization from cold hexane

Sources & evidence

ORD record
ord-4a7b7096c5134fbab93c3c17d90e2645
Source dataset
uspto-grants-2015_03
Patent number
US08969376B2

Reaction notes

Loading…