Hydrochloric Acid → 4-Fluoro-2,3-dihydro-1H-indole

To a stirred suspension of sodium borohydride (560 mg) in diethyl ether (6 ml) was added dropwise zinc chloride (1.0 M solution in diethyl ether, 7.4 ml). The mixture was stirred at room temperature under argon atmosphere for 1 day. To the resultant mixture was added dropwise a solution of 4-fluoroindole (500 mg) in diethyl ether (5 ml). After being stirred at room temperature under argon atmosphere for 12 days, thereto was added a cold 0.5 N aqueous hydrochloric acid solution (30 ml) at 0° C. After that, the mixture was basified with a cold 2 N aqueous sodium hydroxide solution at 0° C., and extracted with ethyl acetate 3 times. The combined organic layer was dried over magnesium sulfate, and the insoluble materials were filtered off, and the filtrate was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (hexane:ethyl acetate=100:0-80:20) to give the titled compound (351 mg) as pale yellow oil. APCI-Mass m/Z 138 (M+H). 1H-NMR (DMSO-d6) δ 2.93 (t, J=8.6 Hz, 2H), 3.46 (t, J=8.6 Hz, 2H), 5.78 (br-s, 1H), 6.24-6.31 (m, 2H), 6.87-6.94 (m, 1H).

1. stirringAfter being stirred at room temperature under argon atmosphere for 12 days
2. extractionextracted with ethyl acetate 3 times
3. dry with materialThe combined organic layer was dried over magnesium sulfate
4. filtrationthe insoluble materials were filtered off
5. customthe filtrate was evaporated under reduced pressure
6. customThe residue was purified by silica gel column chromatography (hexane:ethyl acetate=100:0-80:20)

ORD record

ord-4807ff8b9fd7456d887fb963aa36bf9d

Source dataset

uspto-grants-2011_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07935674B2