反应详情

温度

25 °C

To a solution of tert-butyl 3-(diethoxymethyl)-6-fluoro-4-oxo-spiro[chromane-2,4′-piperidine]-1′-carboxylate (1.3 g, 3.0 mmol) in ethanol (10.4 mL) was added hydrochloric acid (11.1 mL of 4 M, 44.6 mmol) (4 M in dioxane). The reaction mixture was allowed to stir at 25° C. for 2 hours. The solvent was removed under vacuum, and the obtained solid was azeotroped with ethanol (3×30 mL). The resulting beige-white solid was fully dissolved in ethanol (10.40 mL) at 25° C. prior to the addition of tert-butyl N-amino-N-ethyl-carbamate (571.2 mg, 3.6 mmol). The solution was allowed to stir at 25° C. overnight. To the thick beige-white slurry that formed was added hydrochloric acid (3.7 mL of 4 M in dioxane, 14.9 mmol). The mixture was heated at 60° C. to yield a clear yellow solution. After 1 hour at 60° C., a thick white slurry developed. The slurry was allowed to slowly, cool to 25° C. over 4 hours, and solids were collected by vacuum filtration. The cake was rinsed with a 10% solution of EtOH in hexanes (2×). Residual solvent was further removed under reduced pressure providing 1-ethyl-8-fluoro-spiro[chromeno[4,3-c]pyrazole-4,4′-piperidine]hydrochloride (880 mg, 82%). ESI-MS m/z calc. 287.1. found 288.1 (M+1)+. Retention time 0.79 minutes (3 min run). 1H NMR (400 MHz, DMSO) δ 7.52 (dd, J=9.4, 2.8 Hz, 1H), 7.47 (s, 1H), 7.26-7.13 (m, 2H), 5.24 (s, 1H), 4.47 (q, J=7.2 Hz, 2H), 3.30-3.12 (m, 4H), 2.18-2.01 (m, 4H), 1.37 (t, J=7.2 Hz, 3H).

1. customThe solvent was removed under vacuum
2. customthe obtained solid was azeotroped with ethanol (3×30 mL)
3. dissolutionThe resulting beige-white solid was fully dissolved in ethanol (10.40 mL) at 25° C.
4. stirringto stir at 25° C. overnight
5. customTo the thick beige-white slurry that formed
6. temperatureThe mixture was heated at 60° C.
7. customto yield a clear yellow solution
8. waitAfter 1 hour at 60° C.
9. temperaturecool to 25° C. over 4 hours
10. filtrationsolids were collected by vacuum filtration
11. washThe cake was rinsed with a 10% solution of EtOH in hexanes (2×)
12. customResidual solvent was further removed under reduced pressure