Reaktion #353225

Reaktionsgleichung

ethyl acetate

Boc-His(Boc)-OH

DCC

DMF

→

Boc-Histidine(Boc) ester

Ausbeute 38.0%

Reaktionsbedingungen

Aufarbeitung

1. 1
   Filtrationfiltered
2. 2
   WaschenThe ethyl acetate layer was washed with a 2% NaHCO3 solution (2×20 mL), saturated NaCl solution (1×20 mL)
3. 3
   Trocknendried (MgSO4)
4. 4
   workup.ADDITIONPetroleum ether was added
5. 5
   Sonstigea yellowish-green precipitate was collected
6. 6
   SonstigePurification by column chromatography (silica gel; EtOAc; Rf=0.4)

Vorschrift

A mixture of Boc-His(Boc)-OH (506 mg, 1.42 mmol), Compound I-5 (418 mg, 0.92 mmol) and DCC (195 mg, 0.96 mmol) in CE2Cl2 /DMF (1:1, 2.4 mL) was stirred 12 hours at ambient temperature. The reaction mixture was diluted with ethyl acetate (25 mL) and filtered. The ethyl acetate layer was washed with a 2% NaHCO3 solution (2×20 mL), saturated NaCl solution (1×20 mL) and dried (MgSO4). Petroleum ether was added and a yellowish-green precipitate was collected. Purification by column chromatography (silica gel; EtOAc; Rf=0.4) gave 154 mg, (38%) of the Boc-Histidine(Boc) ester as a white solid. 1H NMR (DMSO-d6) δ 1.35 (s, 9H, tBu), 1.48 (s, 9H, tBu). A solution of the product from Example-9 step-1 (144 mg) in EtOAc (2 mL) was added 4N mL). The mixture was stirred for 2 h at room temperature, diluted with water (30 mL) and extracted with EtOAc (1×30 mL) and ether (1×30 mL). The aqueous layer was lyophilized to give a solid product ester (105 mg, 86%), mp 228° C. (dec.), MS m/z=592 (M+1)+.

Quelle