Reaction #632016

Reaction equation

1(R)-tert-butoxycarbonylamino-2(S)-vinyl-cyclopropanecarboxylic acid ethyl ester

LiOH

→

desired compound

Yield 87.3%

1(R)-tert-butoxycarbonylamino-2(S)-vinyl-cyclopropanecarboxylic acid

Yield 87.3%

Solvents

THF

methanol

water

Conditions

Workup

1. 1
   Otherquenched with 1N NaOH (15 mL) and water (20 mL)
2. 2
   WashThe resulting mixture was washed with ethyl acetate (20 mL)
3. 3
   Extractionthe organic phase was extracted with 20 mL 0.5N NaOH
4. 4
   Extractionextracted with ethyl acetate (3×40 mL)
5. 5
   WashThe combined organic extracts were washed with brine
6. 6
   Dryingdried (MgSO4)
7. 7
   Filtrationfiltered
8. 8
   Concentrationconcentrated

Procedure

To a solution of 1(R)-tert-butoxycarbonylamino-2(S)-vinyl-cyclopropanecarboxylic acid ethyl ester (3.28 g, 13.2 mmol) in THF (7 mL) and methanol (7 mL) was added a suspension of LiOH (1.27 g, 53.0 mmol) in water (14 mL). The mixture was stirred overnight at room temperature and quenched with 1N NaOH (15 mL) and water (20 mL). The resulting mixture was washed with ethyl acetate (20 mL), and the organic phase was extracted with 20 mL 0.5N NaOH. The combined aqueous phases were acidified with 1N HCl to pH 4 and extracted with ethyl acetate (3×40 mL). The combined organic extracts were washed with brine, dried (MgSO4), filtered and concentrated to provide the desired compound as a white solid (2.62 g, 87%). 1HNMR: (DMSO-d6) δ 1.22-1.26 (m, 1H), 1.37 (s, 9H), 1.50-1.52 (m, 1H), 2.05 (q, J=9 Hz, 1H), 5.04 (d, J=10 Hz, 1H), 5.22 (d, J=17 Hz, 1H), 5.64-5.71 (m, 1H), 7.18, 7.53 (s, NH (rotamers), 12.4 (br s, 1H)); LC-MS (retention time: 1.67 minutes, method B), MS m/z 228 (M++H).

Source