Trifluoroacetic acid → 3-Dipropylamino-5-nitrochroman

3-Dipropylamino-5-aminochroman (Example 14; 0.050 g, 0.20 mmol) was dissolved in a mixture of trifluoracetic acid (0.080 ml, 1.0 mmol) in water (5 ml). The clear solution was cooled to 0°-4° C. Sodium nitrite (0.017 g, 2.5 mmol) in water (1.0 ml), was added dropwise with good stirring. The solution was stirred for 15 minutes and neutralized with calcium carbonate. A solution of sodium nitrite (0.50 g, 7.2 mmol) in water (1.0 ml) was added followed by a mixture of copper sulfate (0.10 g, 0.62 mmol) and copper (1) oxide in water (1.0 ml). The solution was stirred at 0° C. for 20 minutes and then at ambient temperature for 2 hours. The solution was extracted with diethyl ether. The organic phase was dried with sodium sulfate and evaporated to dryness. The residue was purified by flash chromatography on silica gel by elution with ethyl acetate/hexane 1:9 to give the title compound. Mp 150°-151° C. (hydrochloride).

1. temperatureThe clear solution was cooled to 0°-4° C
2. stirringThe solution was stirred at 0° C. for 20 minutes
3. waitat ambient temperature for 2 hours
4. extractionThe solution was extracted with diethyl ether
5. dry with materialThe organic phase was dried with sodium sulfate
6. customevaporated to dryness
7. customThe residue was purified by flash chromatography on silica gel by elution with ethyl acetate/hexane 1:9

ORD-Eintrag

ord-a544db9b381c4a0992c784867ed75f87

Quelldatensatz

uspto-grants-1996_03

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US05500425