Hydrazine hydrate (1:1) → 6-Methoxy-4-methyl-2H-phthalazin-1-one

Participants

Reaction Conditions

Reaction Steps

To a solution of methyl 2-acetyl-4-methoxybenzoate (5) (2.47 g, 11.86 mmol) in methanol (14.5 mL) is added hydrazine monohydrate (1.78 g, 35.60 mmol). The mixture is stirred at 95° C. under argon for 6 h, the cooled to room temperature, diluted with H2O (50 mL), and extracted with CHCl3 (2×100 mL) and ethyl acetate (100 mL, 2×50 mL, and 2×40 mL). The extracts were washed (brine) and dried. After solvent removal at reduced pressure, the residue is suspended in ethyl acetate (30 mL), heated, cooled, and filtered to give 2.13 g (94%) of 6 as a white solid, mp 252-254° C. IR 3298, 2941, 1732, 1055 cm−1; 1H NMR (CDCl3) δ 2.58 (s, 3H, CH3), 4.00 (s, 3H, CH3O), 7.12 (d, J=1.6 Hz, 1H, 5-PhthH), 7.35 (dd, J=5.6, 1.6 Hz, 1H, 7-PhthH), 8.41 (d, J=5.6 Hz, 1H, 8-PhthH), 10.12 ppm (s, 1H, NH).

Provenance & Evidence