反应详情

Using General Procedure A; ethyl 3,4-dimethoxybenzoylacetate (5.00 g, 19.8 mmol, 1.1 equ.) in ethanol (60 mL) was treated at 0° C. with methylhydrazine (0.95 mL, 19.8 mmol, 1.0 equiv.) to give 3-(3,4-dimethoxyphenyl)-1-methyl-1H-pyrazol-5(4H)-one (1.86 g, 7.94 mmol, 44%) after purification by chromatography on silica gel (hexanes:ethyl acetate; 4:1 to 1:1) as a light yellow powder. 1H-NMR (400 MHz) CDCl3: 7.35-7.35 (d, 1H), 7.06-7.04 (dd, 1H), 6.87-6.85 (d, 1H), 3.94 (s, 3H), 3.92 (s, 3H), 3.57 (s, 2H), 3.39 (s, 3H), 13C-NMR (100 MHz) CDCl3: 171.6, 154.1, 151.1, 149.4, 124.1, 119.6, 110.7, 107.3, 55.9, 55.9, 38.0, 31.3; LC/MS-MS: 235.1→219.0 m/z; GS1 and GS2 at 30, DP=66, CE=33, CXP=14, tR=3.26 min.