Benzyl chloroformate → Boc-dap(Z)-OH

Temperatur

-5 °C

A stirring mixture of the N-Boc-Dap-OH 1 (10.00 g, 49.02 mmol), THF (90 mL), water (30 mL), K2CO3 (13.53 g, 98.04 mmol) and KOH (2.75 g, 49.02 mmol) was cooled to −5° C. Cbz-Cl solution (50 wt % in toluene, 25 mL, 73.53 mmol) was then added dropwise over a period of an hour. The mixture was allowed to stir for 8 h before being concentrated under reduced pressure to remove the THF. The aqueous residue was extracted with diethyl ether (50 mL), acidified to pH 4 by solid citric acid and the resulting precipitate was extracted by CH2Cl2 (2 50 mL). Combined organic layers were dried (Na2SO4) and evaporated to furnish the free acid 2 (15.57 g, 94% yield) as a gummy white solid which was used without further purification. 1H NMR (300 MHz, CDCl3) δ10.76 (1H), 7.25 (5H), 6.24, 5.67 (2H), 5.85 (1H), 5.08, 5.02 (2H), 4.36-4.23 (1H), 3.63-3.35 (2H), 1.38 (9H); 13C NMR (75 MHz, CDCl3)δ 173.5, 157.5, 156.2, 136.4, 128.6, 128.2, 80.6, 67.3, 54.4, 42.9, 28.6.

1. concentrationbefore being concentrated under reduced pressure
2. customto remove the THF
3. extractionThe aqueous residue was extracted with diethyl ether (50 mL)
4. extractionthe resulting precipitate was extracted by CH2Cl2 (2 50 mL)
5. dry with materialCombined organic layers were dried (Na2SO4)
6. customevaporated

ORD-Eintrag

ord-2cb57f19cf16490488ec1898174ca183

Quelldatensatz

uspto-grants-2016_07

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US09394338B2