1,1'-Carbonyldiimidazole → Carbamic acid, N-[(1R,2S)-1-[[(cyclopropylsulfonyl)amino]carbonyl]-2-ethenylcyclopropyl]-, 1,1-dimethylethyl ester

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Reaction Steps

A solution of (1R,2S)-1-((tert-butoxycarbonyl)amino)-2-vinylcyclopropanecarboxylic acid (2.62 g, 11.5 mmol) and CDI (2.43 g, 15.0 mmol) in THF (40 mL) was heated at reflux for 50 min under nitrogen. The solution was cooled to room temperature and transferred by cannula to a solution of cyclopropylsulfonamide (1.82 g, 15.0 mmol) in THF (10 mL). To the resulting solution was added DBU (2.40 mL, 16.1 mmol) and stirring was continued for 20 h. The mixture was quenched with 1N HCl to pH 1 and THF was evaporated in vacuo. The suspension was extracted with EtOAc (2×50 mL) and the combined organic extracts dried (Na2SO4). Purification by recystallization from hexanes-EtOAc (1:1) afforded the title compound (2.4 g) as a white solid. The mother liquor was purified by a Biotage 40S column (eluted 9% acetone in DCM) to give a second batch of the compound tert-butyl ((1R,2S)-1-((cyclopropylsulfonyl)carbamoyl)-2-vinylcyclopropyl)carbamate (1.1 g). Both batches were combined (total yield 92%). 1H NMR: (DMSO-d6) δ ppm 0.96-1.10 (m, 4H), 1.22 (dd, J=5.5, 9.5 Hz, 1H), 1.39 (s, 9H), 1.70 (t, J=5.5 Hz, 1H), 2.19-2.24 (m, 1H), 2.90 (m, 1H), 5.08 (d, J=10 Hz, 1H), 5.23 (d, J=17 Hz, 1H), 5.45 (m, 1H), 6.85, 7.22 (s, NH (rotamers); LC-MS MS m/z 331 (M++H).

Provenance & Evidence