Lithium Hydroxide → (1R,2S)-ethyl 1-(tert-butoxycarbonylamino)-2-cyclopropylcyclopropanecarboxylate

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Reaction Steps

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. To the mixture was added 1.0M NaOH (15 mL), water (20 mL) and ethyl acetate (20 mL). The mixture was shaken, the phases were separated, and the organic phase was again extracted with 20 mL 0.5M NaOH. The combined aqueous phases were acidified with 1.0M HCl until pH=4 and extracted with ethyl acetate (3×40 mL). The combined organic extracts were washed with brine, dried (MgSO4), and filtered to provide the desired product as a white solid (2.62 g, 87%). 1H NMR: (DMSO-d6) δ1.22-1.26 (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 MS m/z 228 (M++H).

Provenance & Evidence