Hydrochloric Acid → Diethyl 1H-pyrrole-2,4-dicarboxylate

HRID 1842445Notes

Reaction equation

HRID 1842445 reaction equation
[H-].[K+].[N+:3]([CH2:5][C:6]([O:8][CH2:9][CH3:10])=[O:7])#[C-:4].[C:11]([O:15][CH2:16][CH3:17])(=[O:14])[C:12]#[CH:13].Cl>CC(OC)(C)C>[NH:3]1[CH:4]=[C:12]([C:11]([O:15][CH2:16][CH3:17])=[O:14])[CH:13]=[C:5]1[C:6]([O:8][CH2:9][CH3:10])=[O:7]

Participants

6

Reactant 4

HCID 313Hydrochloric AcidHCID 12182Ethyl propiolateHCID 82127Potassium hydrideHCID 533707Ethyl isocyanoacetate

Product 1

HCID 12711558Diethyl 1H-pyrrole-2,4-dicarboxylateYield 37.5%

Reagents, catalysts & solvents 1

HCID 15413tert-Butyl methyl etherSolvent2×

Procedure

A suspension of potassium hydride (0.53 g, 13.26 mmol) in MTBE (10 mL) was added to a stirred solution of ethyl 2-isocyanoacetate (1 g, 8.84 mmol) and ethyl propiolate (1 g, 10.19 mmol) in MTBE (10 mL). The resulting mixture was stirred at rt for 4 h. The solution was then acidified with 1N HCl to pH≦3. The organic layer was washed with sat. NaHCO3 solution (2 mL), brine (2 mL), dried (MgSO4), and concentrated to give a solid residue. Purification via flash chromatography (petroleum ether:EtOAc, 15:1 to 10:1) afforded diethyl 1H-pyrrole-2,4-dicarboxylate (0.7 g, 37%). 1H NMR (CDCl3, 300 MHz) δ9.75 (br, 1 H), 7.49 (s, 1 H), 7.24 (s, 1 H), 4.25 (m, 4 H), 1.29 (m, 6 H).

Workup

  1. washThe organic layer was washed with sat. NaHCO3 solution (2 mL), brine (2 mL)
  2. dry with materialdried (MgSO4)
  3. concentrationconcentrated
  4. customto give a solid residue
  5. customPurification via flash chromatography (petroleum ether:EtOAc, 15:1 to 10:1)

Sources & evidence

ORD record
ord-dacd18dd1d004579a27620b38bc2d60f
Source dataset
uspto-grants-2015_02
Patent number
US08946223B2

Reaction notes

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