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6th August 2012 @ 00:23
Reaction successful but in poor yield. Starting material was not entirely clean nor is the product. Used without further purification in PMY 60-2.

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Hydrolysis of PMY 58-2 methyl ester to the acid using aqueous sodium hydroxide.

PMY59-1.png

Reaction Start Time: 12.00 07/08/12
PMY 58-2 (196 mg, 0.62 mmol, 1 equiv.) was dissolved in ethanol (6 mL). A small amount of white powder did not dissolve and was triturated out and kept. Sodium hydroxide (250 mg, 6.2 mmol, 10 equiv.) was dissolved in water (4 mL) and added to the solution of PMY 58-2. After 1.5 hours, reaction complete by TLC. 2M HCl (6 mL) added. The reaction turns hazy but no copious precipitate. The reaction was concentrated under reduced pressure to remove ethanol, crystals form. 2M NaOH (1 mL) added and the mixture gently heated. Crystals do not dissolve. [Still acidic of course, brain malfunction.] Basified to pH14 with dilute NaOH. Washing with DCM results in white suspension/emulsion. Partial separation, DCM layer concentrated to orange solid, PMY 59-2-A. pH adjust of aqueous (approx 60 mL total volume) to ca. pH 10 gave a clear solution. Washed with further DCM (10 mL). HCl added until pH 1, mixture turns cloudy. Extracted with DCM (3 × 20 mL). The combined extracts were washed with brine, dried (MgSO4) and concentrated to a pale yellow solid, PMY 59-2-B (28 mg, 15%). The aqueous layer was concentrated under reduced pressure and triturated with DCM. The combined DCM extracts were washed with brine, dried (MgSO4) and concentrated under reduced pressure to a white solid, PMY 59-2-C.

1H NMR shows:
PMY 59-2-A: unknown impurity.
PMY 59-2-B: Consistent with expected product and impurity. LC/MS consistent shows 301 [M+H]+.

LC/MS:
LCMS


NMR:
1H NMR PMY 59-2-B
1H NMR PMY 59-2-A


See also:
Hydrolysis of PMY 58-2 methyl ester (PMY 59-1)
Scaled-up cyclodehydration of carboxamide PMY 57-2 (PMY 58-2)
Hydrolysis of ethyl 5-methyl-1-phenyl-1H-pyrazole-4-carboxylate (PMY 44-1)
Hydrolysis of Ethyl 1-(4-fluorophenyl)-2,5-dimethyl-1H-pyrrole-3-carboxylate (JRC 2-1)
Hydrolysis of Ethyl 1-(4-fluorophenyl)-2,5-dimethyl-1H-pyrrole-3-carboxylate (PMY 8-2)

Risk and Hazard Assessment:
As for Hydrolysis of Ethyl 1-(4-fluorophenyl)-2,5-dimethyl-1H-pyrrole-3-carboxylate (PMY 8-2)
Linked Posts
Attached Files
LCMS
1H NMR PMY 59-2-A
1H NMR PMY 59-2-B
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