Acetic Acid → 1-(6-Benzyloxycarbonylamino-hexanoyl)-4-oxo-pyrrolidine-3-carboxylic Acid Ethyl Ester

Temperatur

0 °C

To a suspension of potassium t-butoxide (7.12 g, 64 mmol) in toluene (150 mL) at 0° C. under nitrogen, was added diester 59 (20 g, 44 mmol) in toluene (25 mL) over a 10 min period. The solution was stirred for 30 min at 0° C. and 5 mL of glacial acetic acid was added, immediately followed by 25 g of NaH2PO4.H2O in 250 mL of ice-cold water. The resultant mixture was extracted with chloroform (3×200 mL), and the combined organic extracts were washed twice with phosphate buffer (2×25 mL, pH=7.0), dried over anhydrous sodium sulfate and evaporated to dryness. The residue was dissolved in toluene (300 mL), cooled to 0° C., and extracted with cold pH 9.5 carbonate buffer (3×150 mL). The aqueous extracts were converted to pH 3 with phosphoric acid, and extracted with chloroform (5×125 mL) which were combined, dried, and evaporated to a afford keto ester 60 (12 g, 45%).

1. extractionThe resultant mixture was extracted with chloroform (3×200 mL)
2. washthe combined organic extracts were washed twice with phosphate buffer (2×25 mL, pH=7.0)
3. dry with materialdried over anhydrous sodium sulfate
4. customevaporated to dryness
5. dissolutionThe residue was dissolved in toluene (300 mL)
6. temperaturecooled to 0° C.
7. extractionextracted with cold pH 9.5 carbonate buffer (3×150 mL)
8. extractionextracted with chloroform (5×125 mL) which
9. customdried
10. customevaporated to a afford keto ester 60 (12 g, 45%)

ORD-Eintrag

ord-288cb7316ae248cf90e89c26ee4bdaea

Quelldatensatz

uspto-grants-2014_08

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US08796436B2