Trifluoroacetic acid → D-Homophenylalanine allyl ester

The allyl ester from Step A of this Example (1.96 g; 6.136 mmol) was dissolved in dry methylene chloride (10 ml) and anisole (5 ml) was added. The mixture was stirred at room temperature and trifluoroacetic acid was added drop by drop to the ester over 5 minutes. The reaction mixture was stirred at room temperature for a further 2 h then the volatiles removed on a rotary evaporator under reduced pressure to give a thick oil. The oil was dissolved in methylene chloride (50 ml) and shaken with a saturated aqueous solution of sodium bicarbonate. The aqueous layer was discarded and the methylene chloride layer dried over anhydrous magnesium sulfate powder, filtered and the volatiles removed under reduced pressure. The oil that remained after evaporation was chromatographed on silica gel using a solvent gradient beginning with ethyl acetate and hexanes (1:1) to neat ethyl acetate and then with a eluant of ethanol and ethyl acetate in the ratio 1:4 v/v. The product (1.1 g; 81.7%) was isolated after the chromatography. FAB-MS:- calculated for C13H17NO2 219.1; found 219.8 (M).

1. stirringThe reaction mixture was stirred at room temperature for a further 2 h
2. customthe volatiles removed on a rotary evaporator under reduced pressure
3. customto give a thick oil
4. dry with materialthe methylene chloride layer dried over anhydrous magnesium sulfate powder
5. filtrationfiltered
6. customthe volatiles removed under reduced pressure
7. customafter evaporation
8. customwas chromatographed on silica gel using a solvent gradient
9. customThe product (1.1 g; 81.7%) was isolated after the chromatography

ORD record

ord-65e718a8f3934e1487660a0d4b652d2f

Source dataset

uspto-grants-1998_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05726319