Trifluoroacetic acid → 6-fluoro-3-(2-nitroethenyl)-1H-indole

Participants

Reaction Conditions

Reaction Steps

Combine 6-fluoroindole (108 g, 0.8 mol) and dichloromethane (324 ml). Cool in an ice bath. Add trifluoroacetic acid (308 ml) over a few minutes (exothermic). Add a solution of Z-1-dimethylamino-2-nitroethylene (94.7 g, 0.816 mol) in dichloromethane (600 ml) during 40 minutes while maintaining the temperature at about 0-5° C. After 45 minutes, warm to about 20° C. After 2 hours, pour over 1.2 L ice water and stirring overnight with seeding to give a solid. Collect the solid by filtration, wash first with 100 ml of a mixture dichloromethane-cyclohexane 1/1, then with 750 ml of water and dry at 4° C. to give 3-(2-nitrovinyl)-6-fluoroindole.

Provenance & Evidence