Indole → 2-iodo-1H-indole

Temperature

-70 °C

2-iodoindole is prepared according to the following procedure: n-butyllithium (4.2 mL, 2.5 M in solution in hexane) is added, dropwise, to a solution of indole (1.17 g, 10 mmol) in 20 mL of anhydrous THF at −70° C. The resulting suspension is left under stiffing at this temperature for 30 minutes then gaseous CO2 is bubbled through for 10 minutes. The solution which has become clear is then left under stirring for 10 minutes. The solvent and the excess CO2 are evaporated off under vacuum then the resulting solid residue is put into solution in 20 mL of anhydrous THF and cooled down to −70° C. t-butyllithium (6.2 mL; 1.7 M in solution in pentane) is then added dropwise then the resulting solution is left under stirring for 1 hour. 1,2-diiodoethane (2.82 g; 10 mmol) is then added. The reaction mixture is left at −78° C. for 1 hour then treated with 1 mL of water. The resulting solution is left to return to ambient temperature then it is treated with a saturated aqueous solution of NH4Cl. It is extracted with ether. The organic phase obtained is washed with a saturated aqueous solution of NaCl, dried over anhydrous MgSO4 and evaporated under vacuum. The solid residue obtained is purified by flash chromatography on silica gel (hexane/ether, 4/1) producing 2-iodoindole (2.19 g; 9 mmol) with a yield of 90%. The physical and spectral data are described in the article.

1. custom2-iodoindole is prepared
2. customat −70° C
3. waitThe resulting suspension is left
4. customgaseous CO2 is bubbled through for 10 minutes
5. waitThe solution which has become clear is then left
6. customThe solvent and the excess CO2 are evaporated off under vacuum
7. additionis then added dropwise
8. waitthe resulting solution is left
9. stirringunder stirring for 1 hour
10. waitThe reaction mixture is left at −78° C. for 1 hour
11. waitThe resulting solution is left
12. customto return to ambient temperature
13. extractionIt is extracted with ether
14. customThe organic phase obtained
15. washis washed with a saturated aqueous solution of NaCl
16. dry with materialdried over anhydrous MgSO4
17. customevaporated under vacuum
18. customThe solid residue obtained
19. customis purified by flash chromatography on silica gel (hexane/ether, 4/1)

ORD record

ord-805ebb8a04a64da88fd62f34c2a7d56c

Source dataset

uspto-grants-2013_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08343964B2