Tetrahydrofuran → 4-(2-Fluorobenzoyl)-1-methylpiperidine

To a suspension of 7.6 g of magnesium turnings in 25 ml of tetrahydrofuran was added a few drops of ethyl bromide, with stirring under nitrogen. After the reaction began, approximately 50.0 g of N-methyl-4-chloropiperidine in 125 ml of tetrahydrofuran was added dropwise at a rate such as to maintain moderate reflux. The reaction mixture was heated under reflux an additional hr, and 37.2 g of 2-fluorobenzonitrile in 50 ml of tetrahydrofuran was added dropwise. After completion of the addition, the reaction mixture was refluxed for two hrs, and stirred overnight at room temperature. The reaction mixture was poured into a solution of 85 g of ammonium chloride in 1200 ml of ice water and heated on a steam bath for 3 hrs. The mixture was cooled, extracted with benzene (3×250 ml), dried over anhydrous sodium sulfate, and the excess solvent was removed under reduced pressure to give 62.72 g (91%) of 4-(2-fluorobenzoyl)-1-methyl piperidine as an oil. A small amount of 4-(2-fluorobenzoyl)-1-methyl piperidine (1.0 g) was removed, dissolved in ether and a solution of ethereal hydrochloric acid was added. The precipitate was collected, dried and recrystallized from ethanol-ether (2×) to give 0.5 g of 4-(2-fluorobenzoyl)-1-methylpiperidine hydrochloride, mp, 167°-169°.

1. temperatureto maintain moderate reflux
2. temperatureThe reaction mixture was heated
3. temperatureunder reflux an additional hr
4. additionAfter completion of the addition
5. temperaturethe reaction mixture was refluxed for two hrs
6. stirringstirred overnight at room temperature
7. temperatureheated on a steam bath for 3 hrs
8. temperatureThe mixture was cooled
9. extractionextracted with benzene (3×250 ml)
10. dry with materialdried over anhydrous sodium sulfate
11. customthe excess solvent was removed under reduced pressure

ORD record

ord-d4e105d30a20437982fbe4b9a8fbbc8c

Source dataset

uspto-grants-1982_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04355037