Chlorotrimethylsilane → (S)-Methyl 2-((tert-butoxycarbonyl)amino)-3-(cyclopent-1-en-1-yl)propanoate

To a suspension of zinc (123 g, 1.90 mol) in DMF (500 mL) was added TMSCl (46 mL) dropwise. The mixture was stirred at ambient temperature for 45 min. The upper clear liquid was drained out and the residue was washed with DMF (2×200 mL). The resulting solid was re-suspended in DMF (200 mL) and the mixture was cooled to 0° C. A solution of (R)-methyl 2-((tert-butoxycarbonyl)amino)-3-iodopropanoate (104 g, 0.320 mol) in DMF (300 mL) was added. The mixture was stirred at 0° C. under nitrogen for 20 min. The upper clear liquid was drained out and added dropwise to a solution of cyclopent-1-en-1-yl trifluoromethanesulfonate (90 g, 0.37 mol) and Pd(dppf)Cl2 (3.9 g, 4.7 mmol) in DMF (500 mL). After addition, the reaction mixture was stirred at 50° C. under nitrogen overnight then cooled to ambient temperature. Brine (500 mL) was added and the resulting mixture was extracted with MTBE (3×300 mL). The organic layers were combined, washed with brine, and concentrated. The residue was purified by flash column chromatography on silica gel (petroleum ether/EtOAc=100:1 to 40:1) to afford (S)-methyl 2-((tert-butoxycarbonyl)amino)-3-(cyclopent-1-en-1-yl)propanoate as a viscous oil (62 g, 72% yield).

1. washthe residue was washed with DMF (2×200 mL)
2. temperaturethe mixture was cooled to 0° C
3. stirringThe mixture was stirred at 0° C. under nitrogen for 20 min
4. additionAfter addition
5. stirringthe reaction mixture was stirred at 50° C. under nitrogen overnight
6. temperaturethen cooled to ambient temperature
7. extractionthe resulting mixture was extracted with MTBE (3×300 mL)
8. washwashed with brine
9. concentrationconcentrated
10. customThe residue was purified by flash column chromatography on silica gel (petroleum ether/EtOAc=100:1 to 40:1)

ORD record

ord-23e71d1ad3724685973bcae8cbe74eb0

Source dataset

uspto-grants-2016_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09434761B2