Indole → 1-(Phenylsulfonyl)-1H-indole

Temperature

0 °C

To a solution of indole (2.4 g, 20 mol) in dry THF (20 ml) under argon at −78° C. was added dropwise via syringe over 10 min n-butyllithium (1.6M in hexanes; 14 ml). The cooling bath was removed and the solution was stirred for 1 h while warming to 0° C. The resulting indole anion precipitated as a very fine white solid in a cloudy colorless solution. After the suspension was recooled to −78° C., benzenesulfonyl chloride (2.8 ml, 22 mmol) was added via syringe over 20 min, keeping the temperature below −60° C. The resulting colorless mixture was allowed to warm slowly to room temperature overnight, poured into 2% aqueous sodium bicarbonate (30 ml), and extracted with ethyl acetate (2×25 ml). The combined extracts were washed with 2% aqueous sodium bicarbonate(30 ml), water (2×25 ml), dried over anhydrous sodium sulphate, and evaporated to give a light amber oil which crystallized when triturated with 2:1 hexane/ether (15 ml). After standing in the cold (−20° C.) for several hours, the product was collected by filtration, washed with hexane, and dried in vacum to provide pure 1-phenylsulfonyl-indole (60) as white crystals (4.8 g, 90.6%).

1. customThe cooling bath was removed
2. customThe resulting indole anion precipitated as a very fine white solid in a cloudy colorless solution
3. customwas recooled to −78° C.
4. customthe temperature below −60° C
5. temperatureto warm slowly to room temperature overnight
6. extractionextracted with ethyl acetate (2×25 ml)
7. washThe combined extracts were washed with 2% aqueous sodium bicarbonate(30 ml), water (2×25 ml)
8. dry with materialdried over anhydrous sodium sulphate
9. customevaporated
10. customto give a light amber oil which
11. customcrystallized when
12. customtriturated with 2:1 hexane/ether (15 ml)
13. waitAfter standing in the cold (−20° C.) for several hours
14. filtrationthe product was collected by filtration
15. washwashed with hexane
16. customdried in vacum

ORD record

ord-6c08c45fd91942deb6f0277d47f71800

Source dataset

uspto-grants-2005_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06861518B2