反应详情

A mixture of 3-nitro-o-xylene (13.4 mL, 0.1 mol), dimethylformamide dimethyl acetal (40 mL, 0.3 mol) and pyrrolidine (10 mL, 0.12 mol) in 200 mL of dry DMF was heated at 120°-130° C. (oil-bath temperature) under Ar for 21 h. The cooled mixture was poured into cold water (400 mL) and extracted: with ether (4×200 mL). The ethereal solution was washed (H2O, 4×100 mL), dried (Na2SO4) and evaporated to give a dark red viscous oil. This oil was taken up in 150 mL of ethyl acetate, 1.5 g of 10% paliadium-on-charcoal was added and the mixture was hydrogenated at 50 psi on a Parr shaker for 1 h. The reaction mixture was then filtered, the catalyst was washed with additional ethyl acetate and the filtrate was evaporated to give a dark purple oil. Flash cnromatoaraphy (SiO2 /dichloromethane-petroleum ether, 1:1) of this oil gave pure 4-methylindole (8.85 g, 68%) as a light yellow-brown oil: 1H NMR (DMSO-d6, 200 MHz) δ11.04 (br s, 1H), 7.29(t, J=2.7 Hz, 1H), 7.21 (d, J=7.7 Hz, 1H), 6.96 (t J=7.2 Hz, 1H), 6.75 (dr, J=6.9, 0.8 Hz, 1H), 6.43 (m, 1H), 2.46 (s, 3H).

1. temperaturewas heated at 120°-130° C. (oil-bath temperature) under Ar for 21 h
2. extractionextracted
3. washThe ethereal solution was washed (H2O, 4×100 mL)
4. dry with materialdried (Na2SO4)
5. customevaporated
6. customto give a dark red viscous oil
7. filtrationThe reaction mixture was then filtered
8. washthe catalyst was washed with additional ethyl acetate
9. customthe filtrate was evaporated
10. customto give a dark purple oil