Formaldehyde → (R)-Methyl 1-methylpyrrolidine-2-carboxylate

To a solution of sulfuric acid (3.5 ml, 65.3 mmol) in methanol (45 ml) was added D-proline (10.0 g, 86.9 mmol). The mixture was refluxed with stirring for 18 h. The solution was then cooled to 0° C. and neutralised by addition of aqueous potassium carbonate (2.5 M; 10 ml). Formaldehyde (37% solution in water; 11 ml, 136 mmol) was added and the mixture stirred at 0° C. for 15 minutes. Sodium borohydride (1.6 g, 42.3 mmol) was added at 0° C. and the mixture was stirred at room temperature for 3 h. The precipitate was filtered off and the filtrate was partitioned between dichloromethane and water. The isolated aqueous layer was adjusted to pH 10 using solid sodium carbonate and extracted with dichloromethane. The combined organic layers were dried over sodium sulfate and concentrated in vacuo to afford crude (R)-1-methylpyrrolidine-2-carboxylic acid methyl ester (13.13 g).

1. temperatureThe mixture was refluxed
2. stirringthe mixture stirred at 0° C. for 15 minutes
3. stirringthe mixture was stirred at room temperature for 3 h
4. filtrationThe precipitate was filtered off
5. customthe filtrate was partitioned between dichloromethane and water
6. extractionextracted with dichloromethane
7. dry with materialThe combined organic layers were dried over sodium sulfate
8. concentrationconcentrated in vacuo

ORD-Eintrag

ord-793bf44297054be58a442f73a9974de4

Quelldatensatz

uspto-grants-2010_04

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US07700634B2