反应详情

A mixture of 4-(3-isopropyl-[1,2,4]oxadiazol-5-yl)-cyclohexanone (Intermediate 11; 1.6 g, 7.7 mmol) and tert-butyl carbazate (1.12 g, 8.5 mmol) in hexanes (3 mL) was heated at reflux for 3 h, then allowed to cool to room temperature and stand overnight. The white solid was filtered off, washed with hexanes and held under high vacuum to give N′-[4-(3-isopropyl-[1,2,4]oxadiazol-5-yl)cyclohexylidene]-hydrazinecarboxylic acid tert-butyl ester (1.9 g, 77%) as a white solid. 1H NMR (300 MHz, DMSO-d6) δ 1.22 (d, 6H, J=6.9 Hz), 1.41 (s, 9H), 1.60-1.76 (m, 2H), 1.98-2.20 (m, 2H), 2.25-2.36 (m, 2H), 2.75-2.84 (m, 1H), 2.96-3.06 (m, 1H), 3.24-3.35 (m, 2H), 9.62 (br s, 1H).

1. temperaturewas heated
2. temperatureat reflux for 3 h
3. filtrationThe white solid was filtered off
4. washwashed with hexanes