Acetic Anhydride → Ethyl 3-acetyl-4,5-dimethyl-1H-pyrrole-2-carboxylate

HRID 602720Notes

Reaction equation

HRID 602720 reaction equation
[Cl-].[Al+3].[Cl-].[Cl-].[C:5](OC(=O)C)(=[O:7])[CH3:6].[CH2:12]([O:14][C:15]([C:17]1[NH:18][C:19]([CH3:23])=[C:20]([CH3:22])[CH:21]=1)=[O:16])[CH3:13]>ClC(Cl)C>[CH2:12]([O:14][C:15]([C:17]1[NH:18][C:19]([CH3:23])=[C:20]([CH3:22])[C:21]=1[C:5](=[O:7])[CH3:6])=[O:16])[CH3:13]

Participants

5

Reactant 3

HCID 7918Acetic AnhydrideHCID 137478Ethyl 4,5-dimethyl-1H-pyrrole-2-carboxylateHCID 6451240Aluminum(III) Chloride

Product 1

HCID 12288399Ethyl 3-acetyl-4,5-dimethyl-1H-pyrrole-2-carboxylateYield 60%

Reagents, catalysts & solvents 1

HCID 63651,1-DichloroethaneSolvent2×

Procedure

To a solution of aluminum chloride (50.19 g, 0.376 mol) in dry dichloroethane (580 mL) at 25° C. was added slowly acetic anhydride (17.75 mL, 0.188 mol). The resulting mixture was stirred at room temp. for 10 minutes, then a solution of pyrrole 33 (10.49 g, 0.0627 mol) in dichloroethane (30 mL) was added and the reaction mixture was stirred at room temp. for 2 h. After an additional 3 h at 80° C., the mixture was poured into ice water and extracted with dichloromethane. The organic layer was dried with anhy. sodium sulfate and concentrated in vacuo to an orange residue. Short plug filtration over silica gel (30% ethyl acetate/70% hexanes) gave 7.5 g (60%) of ethyl-3-acetyl-4,5-dimethyl-2-pyrrole carboxylate 34. 1H NMR (CDCl3) δ 9.0 (bs, 1H), 4.3 (q, 2H), 2.7 (s, 3H), 2.1 (s, 3H), 1.9 (s, 3H), 1.3 (t, 3H) ppm.

Workup

  1. stirringthe reaction mixture was stirred at room temp. for 2 h
  2. waitAfter an additional 3 h at 80° C.
  3. extractionextracted with dichloromethane
  4. customThe organic layer was dried with anhy
  5. concentrationsodium sulfate and concentrated in vacuo to an orange residue
  6. filtrationShort plug filtration over silica gel (30% ethyl acetate/70% hexanes)

Sources & evidence

ORD record
ord-e9901b5268994389b820915e26e51995
Source dataset
uspto-grants-2011_03
Patent number
US07906550B2

Reaction notes

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