Benzyl chloroformate → HCID 57446950, Verbindung

To a stirred solution of the 5,5,5-trifluoro-L-leucine (12 g) in H2O (150 mL) at 0° C. was added benzyl chloroformate (4.8 mL, 34 mol), followed by dropwise addition of 1 M aqueous NaOH (120 mL, 120 mmol). More benzyl chloroformate (4.8 mL, 34 mmol) was added. The mixture was further stirred at 0° C. and the pH of the mixture became ˜7. The mixture was washed with Et2O (2×) and acidified with aqueous HCl. The aqueous layer was extracted with EtOAc (3×), dried (Na2SO4) and concentrated in vacuo to provide N-[(benzyloxy)carbonyl]-5,5,5-trifluoro-L-leucine. The crude acid was dissolved in Et2O and treated with a solution of diazomethane in Et2O. Chromatography over silica gel and elution with hexanes:Et2O (7:3) gave methyl (4S)—N-[(benzyloxy)carbonyl]-5,5,5-trifluoro-L-leucinate as the less polar fraction.

1. washThe mixture was washed with Et2O (2×)
2. extractionThe aqueous layer was extracted with EtOAc (3×)
3. dry with materialdried (Na2SO4)
4. concentrationconcentrated in vacuo

ORD-Eintrag

ord-5a4990e2d80746a4bfbb65be8bbb82e6

Quelldatensatz

uspto-grants-2012_11

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US08318748B2