Diethyl bromomalonate → Ethyl 1-benzofuran-2-carboxylate

HRID 1263076Notes

Reaction equation

HRID 1263076 reaction equation
[CH2:1]1[CH2:5]OC[CH2:2]1.CCO.C[C:10]([CH3:13])([O-:12])[CH3:11].[K+].Br[CH:16]([C:22](OCC)=O)[C:17]([O:19][CH2:20][CH3:21])=[O:18]>C1COCC1.[Cl-].[Na+].O>[O:12]1[C:10]2[CH:13]=[CH:2][CH:1]=[CH:5][C:11]=2[CH:22]=[C:16]1[C:17]([O:19][CH2:20][CH3:21])=[O:18]

Participants

6

Reactant 3

HCID 69637Diethyl bromomalonateHCID 21873804Tetrahydrofuran ethanolHCID 23665647Potassium tert-butoxide2×

Product 1

HCID 641368Ethyl 1-benzofuran-2-carboxylateYield 85%

Reagents, catalysts & solvents 2

HCID 8028TetrahydrofuranSolvent3×HCID 57417360Sodium chloride; waterSolvent

Procedure

A 3-neck round bottomed flask equipped with a mechanical stirrer, a dropping funnel, a gas inlet tube, and a thermometer is charged with 24.4 g (0.2 mol) of salicyl aldehyde (Aldrich) and 800 ml of THF-EtOH (19:1) under a nitrogen atmosphere. To this solution 150 ml (0.24 mol) of potassium t-butoxide in THF (1.6M) is added dropwise over 20 min at room temperature. A milky yellow precipitate is formed during the addition. The mixture is stirred at room temperature for one hr. A solution of 57.4 g (0.24 mol) of diethyl bromomalonate (Aldrich) in 20 ml of THF is added dropwise over 10 min. The mixture becomes grayish in color. After stirring for one hr at room temperature, another portion of potassium t-butoxide in THF (150 ml, 0.24 mol) is added dropwise over 40 min at room temperature. TLC shows no starting material remaining after an additional 40 min of stirring. The mixture is poured into 500 ml of brine mixed with crushed ice and extracted twice with ethyl acetate (1 L). The organic phase is washed with brine and dried over anhydrous magnesium sulfate. Filtration and concentration affords a deep brown oil. Vacuum distillation affords pure ethyl benzofuran-2-carboxylate (boiling point 88°-91° C./0.03 mm, 32.5 g, 85%).

Workup

  1. customA 3-neck round bottomed flask equipped with a mechanical stirrer, a dropping funnel, a gas inlet tube
  2. customA milky yellow precipitate is formed during the addition
  3. stirringAfter stirring for one hr at room temperature
  4. waitremaining after an additional 40 min
  5. stirringof stirring
  6. additionmixed with crushed ice
  7. extractionextracted twice with ethyl acetate (1 L)
  8. washThe organic phase is washed with brine
  9. dry with materialdried over anhydrous magnesium sulfate
  10. filtrationFiltration and concentration
  11. customaffords a deep brown oil
  12. distillationVacuum distillation

Sources & evidence

ORD record
ord-87689f1053cf496789c4634387bf9dfd
Source dataset
uspto-grants-1984_06
Patent number
US04455427

Reaction notes

Loading…