6-Fluoro-2-nitrobenzyl cyanide → 4-Fluoro-1,3-dihydro-2H-indol-2-one

6-Fluoro-2-nitrobenzyl cyanide (23.10 g, 0.12 mole) (prepared according to A. Kalir, Synthesis (1987) 514-515) was dissolved in 10:1 MeOH/H2O (250 mL) and the solution was chilled in an ice water bath. HBr gas was bubbled into the cold mixture for 75 min. The solution was allowed to warm up to r.t. and then concentrated to half its volume under reduced pressure. THF (100 mL), water (100 mL) and conc. HCl (6 mL) were successively added at r.t. and stirring was maintained for 75 min. The mixture was poured into water and extracted with ethyl acetate. The combined organic layers were washed with water, sat. aq. NaHCO3 and brine, then dried over sodium sulfate and concentrated under educed pressure. This material (20.9 g) was dissolved in acetic acid (200 mL) and hydrogenated for 2 h in a Parr apparatus at 50 Psi, in the presence of 10% Pd/C (4.33 g). The reaction mixture was filtered through a cake of Celite®, and the cake was washed with acetic acid. The solution was concentrated under reduced pressure and dissolved in MeOH (300 mL) containing 1N NaOH (15 mL). This mixture was poured into 2:1 sat aq. NaCl/H2O (600 mL) and extracted with ethyl acetate. The combined organic layers were washed with brine, dried over sodium sulfate and concentrated. The crude residue was triturated with ether to afford 5.8 g (first crop) of pure 1,3-dihydro-4-fluoro-2H-indol-2-one. The mother liquor was chromatographed on Silica Gel (230-400 mesh, eluted with 40% ethyl acetate in hexanes) to yield 16 g of product (overall yield from cyanide: 41%).

1. customKalir, Synthesis (1987) 514-515)
2. temperaturethe solution was chilled in an ice water bath
3. customHBr gas was bubbled into the cold mixture for 75 min
4. concentrationconcentrated to half its volume under reduced pressure
5. additionTHF (100 mL), water (100 mL) and conc. HCl (6 mL) were successively added at r.t.
6. temperaturewas maintained for 75 min
7. additionThe mixture was poured into water
8. extractionextracted with ethyl acetate
9. washThe combined organic layers were washed with water, sat. aq. NaHCO3 and brine
10. dry with materialdried over sodium sulfate
11. concentrationconcentrated under educed pressure
12. dissolutionThis material (20.9 g) was dissolved in acetic acid (200 mL) and hydrogenated for 2 h in a Parr apparatus at 50 Psi, in the presence of 10% Pd/C (4.33 g)
13. filtrationThe reaction mixture was filtered through a cake of Celite®
14. washthe cake was washed with acetic acid
15. concentrationThe solution was concentrated under reduced pressure
16. dissolutiondissolved in MeOH (300 mL)
17. additioncontaining 1N NaOH (15 mL)
18. additionThis mixture was poured into 2:1
19. extractionextracted with ethyl acetate
20. washThe combined organic layers were washed with brine
21. dry with materialdried over sodium sulfate
22. concentrationconcentrated
23. customThe crude residue was triturated with ether

ORD-Eintrag

ord-d8cf3c988e064a6594e61936bf0e0f4a

Quelldatensatz

uspto-grants-2001_03

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US06197804B1