Phenylhydrazine → 3-Ethyl-1-phenyl-1H-pyrazol-5-amine

HRID 631710Notes

Reaction equation

O=[C:2]([CH2:6][CH3:7])[CH2:3][C:4]#[N:5].[C:8]1([NH:14][NH2:15])[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=1>C(O)C>[CH2:6]([C:2]1[CH:3]=[C:4]([NH2:5])[N:14]([C:8]2[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=2)[N:15]=1)[CH3:7]

Participants

Conditions

Temperature: 90 °C

Procedure

A stirred mixture of 3-oxopentanenitrile (19.42 g, 0.20 mol) and phenylhydrazine (23.62 g, 0.20 mol) in ethanol (200 mL) was heated at 90° C. for 15 h. The reaction mixture was quenched with water and extracted with dichloromethane. The combined dichloromethane layers were dried over magnesium sulfate, concentrated under reduced pressure, and dried under vacuum to afford the light yellow oil which was purified by silica gel flash column chromatography (eluting with a mixture of 20% ethyl acetate in petroleum ether). The obtained solid was recrystallized from a mixture of 10% petroleum ether in ethyl acetate, to afford 3-ethyl-1-phenyl-1H-pyrazol-5-amine (14 g, 37% over two steps) as a yellow solid. 1H NMR (400 MHz, DMSO-d6) δ7.57-7.59 (m, 2H), 7.43-7.46 (m, 2H), 7.27 (m, 1H), 5.36 (s, 1H), 5.26 (s, 2H), 2.45 (q, J=7.6 Hz, 2H), 1.15 (t, J=7.6 Hz, 3H); LC-MS (ESI) m/z 188 (M+H)+.

Workup

customThe reaction mixture was quenched with water
extractionextracted with dichloromethane
dry with materialThe combined dichloromethane layers were dried over magnesium sulfate
concentrationconcentrated under reduced pressure
customdried under vacuum
customto afford the light yellow oil which
customwas purified by silica gel flash column chromatography (
washeluting with a mixture of 20% ethyl acetate in petroleum ether)
customThe obtained solid was recrystallized from a mixture of 10% petroleum ether in ethyl acetate

Sources & evidence

ORD record: ord-c7e805aad2ae4700a82377d2862ba87c
Source dataset: uspto-grants-2016_04
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US09320739B2

Reaction notes

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