Hydrazine hydrate (1:1) → Ethyl 4,5,6,7-tetrahydro-1H-indazole-5-carboxylate

反応式

O=[C:2]1[CH2:7][CH2:6][CH:5]([C:8]([O:10][CH2:11][CH3:12])=[O:9])[CH2:4][CH2:3]1.O.[NH2:14]N.C[N:17]([CH:19](OC)OC)C>C(O)C>[NH:14]1[C:2]2[CH2:7][CH2:6][CH:5]([C:8]([O:10][CH2:11][CH3:12])=[O:9])[CH2:4][C:3]=2[CH:19]=[N:17]1

参加物

実験手順

A solution of ethyl 4-oxocyclohexanecarboxylate (50 g, 0.29 mol) in DMF-DMA (275 mL) was heated at 110° C. for 12 h. The mixture was concentrated and hydrazine hydrate (73.5 g, 1.47 mol) in ethanol (1000 mL) was heated under reflux overnight. Most of ethanol was removed and the remaining mixture was treated with water (400 mL). The resulting mixture was extracted with EtOAc (400 ml×2). The combined organic layers were washed with brine (400 mL) and concentrated. The residue was purified by flash column chromatography on silica gel (DCM/MeOH=30:1) to afford crude ethyl 4,5,6,7-tetrahydro-1H-indazole-5-carboxylate (18 g) as a colorless solid.