Methanol → Methyl 3-(4-methyl-1H-pyrrol-3-yl)propanoate

Temperature

70 °C

3-(2-Carboxyethyl)-4-methylpyrrole (123 g) was mixed with 1500 mL of ethyl ether and 250 mL of methanol in a magnetically stirred receiver flask. A separate 3 L, 3 neck round bottom flask was equipped with magnetic stirring, a distillation head and condenser leading to the inlet of the receiver flask, and heated in a water bath. Into the 3 L flask was placed 240 g of Diazald, dissolved in 1800 mL of ethyl ether, and a solution of 73 g of potassium hydroxide, dissolved in 360 mL of 95% ethanol and 112 mL of water. The 3 L flask was stirred and heated to 65-75° C. in a water bath, and the diazomethane-ether mixture was distilled into the stirred receiver flask over about 2.5 hrs. Ethyl ether (200 mL) was added to the 3 L flask, and the distillation continued until complete. The receiver flask was stirred for another 30 minutes, and then 10 mL of acetic acid was added. The mixture was extracted twice with 500 mL of water each time, and then twice with 200 mL of saturated sodium bicarbonate each time. The ether layer was dried over anhydrous sodium sulfate, and distilled to leave a dark fluid residue. The residue was distilled twice through a 4 inch Vigreux column and once through a 10 inch vacuum-jacketed Vigreux column to give 108 g (80.6% yield) of 3-(2-methoxycarbonylethyl)-4-methylpyrrole. BP 108-113 C at 0.5 mm.

1. customA separate 3 L, 3 neck round bottom flask was equipped with magnetic stirring
2. temperatureheated in a water bath
3. distillationthe diazomethane-ether mixture was distilled into the stirred receiver flask over about 2.5 hrs
4. additionEthyl ether (200 mL) was added to the 3 L flask
5. distillationthe distillation
6. stirringThe receiver flask was stirred for another 30 minutes
7. addition10 mL of acetic acid was added
8. extractionThe mixture was extracted twice with 500 mL of water each time
9. dry with materialThe ether layer was dried over anhydrous sodium sulfate
10. distillationdistilled
11. customto leave a dark fluid residue
12. distillationThe residue was distilled twice through a 4 inch Vigreux column and once through a 10 inch vacuum-jacketed Vigreux column

ORD record

ord-abbc9b91b9f34b52bbe8eed8afea6db6

Source dataset

uspto-grants-2005_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06846839B1