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2nd October 2012 @ 06:42
Scale-up of PMY 8-3 hydrolysis of Ethyl 1-(4-fluorophenyl)-2,5-dimethyl-1H-pyrrole-3-carboxylate to give the desired acid (1-(4-Fluorophenyl)-2,5-dimethyl-1H-pyrrole-3-carboxylic acid).

Reaction Scheme

Overall yield: 4.68 g, 20 mmol, 87% yield)

AEW 7-1 (6.0 g, 23.0 mmol, 1 equiv.) was dissolved in EtOH (60 mL) and 20% NaOH (40 mL, approx 8.5 equiv.). Heated to reflux. After 16 hours reaction was complete by TLC. Reaction was allowed to cool to room temperature then in ice. Acidified (pH 1) with 2M HCl and then cooled in an ice bath for 30 minutes. White powder was filtered and washed with ice cold water to yield a pale brown solid on drying (AEW 10-1 A, 1.24 g, 5.33 mmol, 23% yield). The mother liquors were concentrated until a brown solid crashed out and then left to cool in the freezer, prior to filtration and washing with ice cold water to yield a crystalline brown solid (AEW 10-1 B, 3.44 g, 14.8 mmol, 64% yield). Comparison of 1H NMR data showed both fractions to be of equal purity and so they were combined. Overall yield: 4.68 g, 20 mmol, 87% yield).

TLC (25% EtOAC/petrol) visualised with UV and vanillin:

AEW 10-1.jpg

NMR:
AEW 10-1-A.zip
AEW 10-1A.pdf



Risk and Hazard Assessment:
As for Hydrolysis of Ethyl 1-(4-fluorophenyl)-2,5-dimethyl-1H-pyrrole-3-carboxylate (PMY 8-1)

See also:
Hydrolysis of Ethyl 1-(4-fluorophenyl)-2,5-dimethyl-1H-pyrrole-3-carboxylate (PMY 8-3)
Hydrolysis of Ethyl 1-(4-fluorophenyl)-2,5-dimethyl-1H-pyrrole-3-carboxylate (PMY 8-2)
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Attached Files
AEW 10-1.png
AEW 10-1.jpg
AEW 10-1A.pdf
AEW 10-1-A.zip