tert-Butyl Formate → (1R,4S)-4-[(tert-Butoxycarbonyl)amino]-1-[(3R)-tetrahydrofuran-3-yl]cyclopent-2-ene-1-carboxylic acid

To a solution of methyl (1R,4S)-4-[(tert-butoxycarbonyl)amino]-1-[(3R)-tetrahydrofuran-3-yl]cyclopent-2-ene-1-carboxylate (1.60 g, 5.14 mmol) in tetrahydrofuran (27.8 mL), methanol (27.8 mL) and water (6.0 mL) was added lithium hydroxide monohydrate (0.346 g, 8.25 mmol). The pink mixture was heated to reflux for 18 h. The organic solvents were removed in vacuo and the aqueous layer was extracted once with ether and then acidified slowly with 6 M HCl until the pH reached 3-4. The resulting suspension was extracted with CH2Cl2 three times. The combined organic layers were dried over MgSO4, filtered and concentrated to give the product as a mixture of two cis/trans isomers (1.59 g) as a light yellow solid. MS calculated for C15H24NO5: (M+H) 298.2; found 198.2 (M+H-Boc).

1. temperatureThe pink mixture was heated
2. temperatureto reflux for 18 h
3. customThe organic solvents were removed in vacuo
4. extractionthe aqueous layer was extracted once with ether
5. extractionThe resulting suspension was extracted with CH2Cl2 three times
6. dry with materialThe combined organic layers were dried over MgSO4
7. filtrationfiltered
8. concentrationconcentrated
9. customto give the product
10. additionas a mixture of two cis/trans isomers (1.59 g) as a light yellow solid

ORD-Eintrag

ord-b4af25f1426c499f9d89c7f7dc788b86

Quelldatensatz

uspto-grants-2008_11

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US07449467B2