Methylhydrazine → 6-Bromo-3-ethyl-1-methylindazole

HRID 849315Notizen

Reaktionsgleichung

[Br:1][C:2]1[CH:3]=[CH:4][C:5]([C:13](=O)[CH2:14][CH3:15])=[C:6](OS(C)(=O)=O)[CH:7]=1.[CH3:17][NH:18][NH2:19].C([O-])(=O)C.[NH4+]>ClCCl>[Br:1][C:2]1[CH:7]=[C:6]2[C:5]([C:13]([CH2:14][CH3:15])=[N:19][N:18]2[CH3:17])=[CH:4][CH:3]=1

Komponenten

Reaktionsbedingungen

Temperatur: 135 °C

Versuchsvorschrift

Methanesulfonic acid 5-bromo-2-propionyl-phenyl ester (2.00 g, 6.51 mmol) was combined with methylhydrazine (0.69 mL, 13 mmol) and ammonium acetate (1.30 g, 16.9 mmol) in xylenes (12 mL). The reaction mixture was heated to 135° C. for 18 hours using a Dean Stark apparatus. The reaction was cooled to room temperature, diluted with dichloromethane (50 mL), and washed with water (50 mL) and 1N aqueous hydrochloric acid (50 mL). The organic extracts were dried over magnesium sulfate and concentrated. The crude product was purified by chromatography on silica gel eluting with 4:1 hexanes/ethyl acetate to yield 1.20 g of 6-bromo-1-methyl-3ethyl-1H-indazole (75% yield). 1H NMR (400 MHz, CDCl3) δ 1.35 (t, 3, J=7.7), 2.94 (q, 2, J=7.7), 3.95 (s, 3), 7.18 (dd, 1, J=8.5, 1.5), 7.50 (d, J=0.8), 7.52 (dd, 1, J=8.5, 0.6). 13C NMR (100 MHz, CDCl3) δ 13.66, 20.29, 35.21, 111.82, 120.61, 121.35, 121.60, 123.05, 141.68, 147.08. IR 2970, 2935, 1609, 1506, 1458, 1223, 1047, 819, 805 cm-1. Analysis calculated for C10H11BrN2 : C, 50.23; H, 4.64; N, 11.72. Found: C, 50.14; H, 4.57; N, 11.46.

Aufarbeitung

temperatureThe reaction was cooled to room temperature
washwashed with water (50 mL) and 1N aqueous hydrochloric acid (50 mL)
dry with materialThe organic extracts were dried over magnesium sulfate
concentrationconcentrated
customThe crude product was purified by chromatography on silica gel eluting with 4:1 hexanes/ethyl acetate

Quellen und Nachweise

ORD-Eintrag: ord-c13183bd6541483082acabe1ee044b9d
Quelldatensatz: uspto-grants-2000_01
DOI: 10.6084/m9.figshare.5104873.v1
Patentnummer: US06011159

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