Sulfuric Acid → 3-Methyl-5-(1-methyl-2(S)-pyrrolidinyl)isoxazole

Temperature

0 °C

To a stirred suspension of sodium borohydride (7.59 g, 200 mmol) in 100 mL of THF cooled to 0° C. was added a solution of 20 g (80.28 mmol) of N-Cbz-L-proline, from step 24a above, in 50 mL of ether. To this solution was added dropwise a solution of 5 mL of H2SO4 in 20 mL of ether, with stirring and while maintaining the temperature below 20° C. The reaction mixture was warmed to room temperature and stirred for 16 hr. The reaction was quenched by the addition of 100 mL of methanol dropwise. The solvents were removed, 30 mL of 4N NaOH was added, and the mixture was extracted with ethyl acetate. The organic extract was dried over Na2SO4 and concentrated to afford the title product, 16.61 g (88 % yield).

1. temperaturewhile maintaining the temperature below 20° C
2. temperatureThe reaction mixture was warmed to room temperature
3. stirringstirred for 16 hr
4. customThe reaction was quenched by the addition of 100 mL of methanol dropwise
5. customThe solvents were removed
6. addition30 mL of 4N NaOH was added
7. extractionthe mixture was extracted with ethyl acetate
8. extractionThe organic extract
9. dry with materialwas dried over Na2SO4
10. concentrationconcentrated

ORD record

ord-c9a6f38691244cecb730d2b45b58285c

Source dataset

uspto-grants-1995_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05424444