反应详情

温度

159 °C

Ethyl N-(2-methyl-6-ethylphenyl)formimidate (65.9 g.) in 50 ml. of di-n-butylamine was slowly added, over about 5 minutes, to the potassium di-n-butylamide reaction mixture at 20° C. The metallation and cyclization reactions were substantially instantaneous under these reaction conditions. The transient appearance of a deep red color characteristic of benzyl anion was developed and discharged immediately upon contact of ethyl N-(2-methyl-6-ethylphenyl)formimidate with the potassium amide reaction mixture near the neck of the reactor. All solids dissolved resulting in a light brownish solution. Stirring was continued for another half hour. Then 150 ml. of ethyl alcohol were added to destroy the excess amide and unreacted metal and also to convert potassium indole salt to indole. After the removal of the excess alcohol at reflux temperature (159° C.) through a distillating column packed with Fenske packing materials, a brown oily material separated and settled at the bottom of the flask. The top amine layer was decanted off. The brown oily layer was dissolved in 300 ml. of hexane, then washed with 500 ml. water which was extracted with two 300 ml. portions of hexane. The combined hexane extracts were dried over Na2SO4 and filtered. Evaporation of volatile components furnished 39.8 g. of 7-ethylindole (80.0 percent yield) of over 98.5 percent purity.

1. customThe metallation and cyclization reactions were substantially instantaneous under these reaction conditions
2. dissolutionAll solids dissolved
3. customresulting in a light brownish solution
4. customto destroy the excess amide and unreacted metal
5. customAfter the removal of the excess alcohol
6. customa brown oily material separated
7. customThe top amine layer was decanted off
8. dissolutionThe brown oily layer was dissolved in 300 ml
9. washof hexane, then washed with 500 ml
10. extractionwater which was extracted with two 300 ml
11. dry with materialThe combined hexane extracts were dried over Na2SO4
12. filtrationfiltered
13. customEvaporation of volatile components
14. customfurnished 39.8 g