Sodium borohydride → Benzyl ((2S,3S)-4-chloro-3-hydroxy-1-phenylbutan-2-yl)carbamate

To a solution of N-benzyloxycarbonyl-L-phenylalanine chloromethyl ketone (75 g, 0.2 mol) in a mixture of 800 mL of methanol and 800 mL of tetrahydrofuran was added sodium borohydride (13.17 g, 0.348 mol, 1.54 equiv.) over 100 min. The solution was stirred at room temperature for 2 hours and then concentrated in vacuo. The residue was dissolved in 1000 mL of ethyl acetate and washed with 1N KHSO4, saturated aqueous NaHCO3, saturated aqueous NaCl, dried over anhydrous MgSO4, filtered and concentrated in vacuo to give an oil. The crude product was dissolved in 1000 mL of hexanes at 60° C. and allowed to cool to room temperature where upon crystals formed that were isolated by filtration and washed with copious amounts of hexanes. This solid was then recrystallized from hot ethyl acetate and hexanes to provide 32.3 g 43% of N-benzyloxycarbonyl-3(S)-amino-1-chloro-4-phenyl-2(S)-butanol, mp 150–151° C., FAB MS: MLi+=340.

1. concentrationconcentrated in vacuo
2. dissolutionThe residue was dissolved in 1000 mL of ethyl acetate
3. washwashed with 1N KHSO4, saturated aqueous NaHCO3, saturated aqueous NaCl
4. dry with materialdried over anhydrous MgSO4
5. filtrationfiltered
6. concentrationconcentrated in vacuo
7. customto give an oil
8. temperatureto cool to room temperature where upon crystals
9. customformed
10. customthat were isolated by filtration
11. washwashed with copious amounts of hexanes
12. customThis solid was then recrystallized from hot ethyl acetate and hexanes

ORD-Eintrag

ord-bf1a1dda016e411284aba31e2971cca8

Quelldatensatz

uspto-grants-2006_08

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US07091219B2