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

Participants

Reaction Conditions

Reaction Steps

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.

Provenance & Evidence