Hydrazine hydrate (1:1) → 7-methoxy-4-methyl-2H-phthalazin-1-one

Participants

Reaction Conditions

Reaction Steps

To a solution of methyl 2-acetyl-5-methoxybenzoate (2) (2.21 g, 10.60 mmol) in methanol (13 mL) is added hydrazine monohydrate (1.59 g, 31.80 mmol). The mixture is stirred at 95° C. under argon for 5 h, then cooled to room temperature, diluted with H2O (50 mL), and extracted with ethyl acetate (2×100 mL, 2×50 mL, and 2×30 mL). The extract is washed (brine), dried, and concentrated at reduced pressure. The residue is suspended in ethyl acetate (20 mL), heated, then cooled, and filtered to give 1.92 g (95%) of 3 as a white solid, mp 203-205° C. IR 3314, 2918, 1652, 1241 cm−1; 1H NMR (CDCl3) δ 2.60 (s, 3H, CH3), 4.01 (s, 3H, CH3O), 7.42 (dd, J=9.0, 2.7 Hz, 1H, 6-PhthH), 7.75 (d, J=9.0 Hz, 1H, 5-PhthH), 7.88 (d, J=2.7 Hz, 1H, 8-PhthH), 10.75 ppm (s, 1H, NH).

Provenance & Evidence