Hydrazine hydrate (1:1) → 6-phenoxy-3-styryl-4,5-dihydro-1H-indazole

HRID 2181511Notes

Reaction equation

O([C:8]1[CH2:13][CH2:12][CH2:11][C:10](=O)[C:9]=1[C:15](=O)[CH:16]=[CH:17][C:18]1[CH:23]=[CH:22][CH:21]=[CH:20][CH:19]=1)C1C=CC=CC=1.[OH2:25].[NH2:26][NH2:27]>CC(O)=O.CCO>[O:25]([C:12]1[CH2:11][CH2:10][C:9]2[C:15]([CH:16]=[CH:17][C:18]3[CH:19]=[CH:20][CH:21]=[CH:22][CH:23]=3)=[N:26][NH:27][C:8]=2[CH:13]=1)[C:8]1[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=1

Participants

Conditions

Temperature: 70 °C

Procedure

To a stirred solution of 3-phenoxy-(3-phenyl-acryloyl)-cyclohex-2-enone (1.13 g, 3.55 mmol) in 20 mL of HOAc/EtOH (1:1) was added hydrazine monohydrate (0.21 mL, 4.3 mmol). The reaction was heated at 70° C. for 3 h, cooled and poured cautiously into saturated Na HCO3 solution and extracted with EtOAc (2×). The combined organic layers were washed with saturated NaCl solution, dried (MgSO4) and concentrated under reduced pressure. The residue was chromatographed on silica gel eluting hexanes/EtOAc (2:1) to give 6-phenoxy-3-styryl-4,5-dihydro-1H-indazole (3) as an off-white solid (406 mg, 36%): 1H NMR (DMSO-d6) δ 2.64 (t, 2H, J=8.0 Hz), 2.95 (t, 2H, J=8.0 Hz), 5.46 (s, 1H), 7.04 (AB, 2H, J=16.8 Hz), 7.15 (d, 2H, J=8.1 Hz), 7.25 (m, 2H), 7.42 (m, 4H), 7.55 (d, 2H, J=7.7 Hz), 12.44 (s, 1H). Anal. Calc. for C2H18N2O.0.2H2O: C, 79.32; H, 5.83; N, 8.81. Found: C, 79.36; H, 5.85; N, 8.84.

Workup

temperaturecooled
extractionextracted with EtOAc (2×)
washThe combined organic layers were washed with saturated NaCl solution
dry with materialdried (MgSO4)
concentrationconcentrated under reduced pressure
customThe residue was chromatographed on silica gel
washeluting hexanes/EtOAc (2:1)

Sources & evidence

ORD record: ord-0354433644994171a3d702f97cd1b430
Source dataset: uspto-grants-2005_05
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US06891044B2

Reaction notes

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