反应详情

tert-Butyl 2-oxo-1,2-dihydrospiro[benzo[d][1,3]oxazine-4,4′-piperidine]-1′-carboxylate (6.71 g, 21.1 mmol) was dissolved in dichloromethane (50 mL), treated with trifluoroacetic acid (20 mL) and stirred at room temperature for 45 min. The reaction was concentrated under reduced pressure, re-dissolved in acetonitrile and re-concentrated under reduced pressure. The crude TFA salt was cooled in an ice-H2O bath, dissolved in ice-cold saturated brine (20 mL) and H2O (50 mL) and basified with ice-cold 35% NaOH (aq). A small amount of product (obtained from extraction with 50 mL ethyl acetate) was added to the aqueous layer to initiate crystallization. The suspension obtained was cooled in an ice-H2O bath, filtered, rinsed with ice-cold H2O and dried to afford 3.071 g spiro[benzo[d][1,3]oxazine-4,4′-piperidin]-2(1H)-one free base as a white crystalline solid. An additional 800 mg free base was obtained via extraction of the mother liquor with ethyl acetate (10×50 mL) and subsequent trituration of the crude free base with acetonitrile (overall yield=84%). LC/MS m/z 219.2 [M+H]+, retention time 0.58 min (RP—C18, 10-99% CH3CN/0.05% TFA); 1H-NMR (400 MHz, DMSO-d6) δ 10.17 (br s, 1H), 7.23 (m, 2H), 7.02 (m, 1H), 6.87 (dd, J=8.2, 1.2 Hz, 1H), 2.89 (m, 2H), 2.82 (m, 2H), 1.84 (m, 4H).

1. concentrationThe reaction was concentrated under reduced pressure
2. dissolutionre-dissolved in acetonitrile
3. concentrationre-concentrated under reduced pressure
4. temperatureThe crude TFA salt was cooled in an ice-H2O bath
5. dissolutiondissolved in ice-cold saturated brine (20 mL)
6. customA small amount of product (obtained from extraction with 50 mL ethyl acetate)
7. additionwas added to the aqueous layer
8. customcrystallization
9. customThe suspension obtained
10. temperaturewas cooled in an ice-H2O bath
11. filtrationfiltered
12. washrinsed with ice-cold H2O
13. customdried