反应详情

A solution of 4,5-dimethyl-3-nitrobenzoic acid (Helv. Chim. Acta 1980, 37, 385; 2.50 g, 12.8 mmol) and N,N-dimethylformamide dimethyl acetal (3.66 g, 30.7 mmol) in N,N-dimethylformamide (25 mL) was heated at 140° C. for 4 h, then volatile material was removed by distillation. The residue was taken up in tetrahydrofuran (10 mL) and methanol (10 mL), then Raney nickel (aqueous suspension, 1 mL) and hydrazine hydrate (1.85 g, 57.6 mmol) were added over 30 min in three portions at 50° C., and the reaction was kept at 50° C. for another 90 min. The reaction mixture was filtered through diatomaceous earth, the filtrate was dried (MgSO4), and evaporated. Chromatography (SiO2, heptane-ethyl acetate 2:1) produced 4-methyl-1H-indole-6-carboxylic acid methyl ester (1.68 g, 69%). White solid, MS (ISP): m/e 190.3 (M+H).

1. customvolatile material was removed by distillation
2. filtrationThe reaction mixture was filtered through diatomaceous earth
3. dry with materialthe filtrate was dried (MgSO4)
4. customevaporated