1,3-Dibromopropane → 2-Isoxazolidinecarboxylic acid, ethyl ester

To a solution of KOH (6.4 g, 0.11 mol) and hydroxyurethane (12 g, 0.11 mol) in ethanol (50 mL) was added 1,3-dibromopropane (5.8 mL, 0.057 mol). The resulting suspension was heated at reflux for 1 hour. After the mixture was cooled to room temperature, an additional portion of KOH (3.2 g, 0.055 mol) and of dibromopropane (2.9 mL, 0.028 mol) was added. The mixture was then refluxed for 1 hour, cooled to room temperature, and solvent was evaporated. The residue was suspended in boiling ether three times and filtered. The combined filtrates were dried over sodium sulfate, filtered, and evaporated. A portion of 3 g of the crude product was purified by flush column chromatography (EtOAC/Hexane, gradient elution), yielding 1.18 g of N-(ethoxycarbonyl)isoxazolidine. 1H NMR (CDCl3) δ 1.15 (t, 3H), 2.15 (q, 2H), 3.55 (t, 2H), 3.8 (t, 2H), 4.1 (q, 2H).

1. temperatureThe resulting suspension was heated
2. temperatureat reflux for 1 hour
3. temperatureThe mixture was then refluxed for 1 hour
4. temperaturecooled to room temperature
5. customsolvent was evaporated
6. filtrationfiltered
7. dry with materialThe combined filtrates were dried over sodium sulfate
8. filtrationfiltered
9. customevaporated
10. customA portion of 3 g of the crude product was purified
11. customby flush
12. washcolumn chromatography (EtOAC/Hexane, gradient elution)

ORD record

ord-7cf97349cb774865b84448fdfe0c9540

Source dataset

uspto-grants-2004_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06680317B2