8-Amino-2-naphthalenol → 8-Amino-1,2,3,4-tetrahydronaphthalen-2-ol

Temperature

85 °C

Ethanol (1 L) was added to 8-amino-2-naphthol (100 g, 610 mmol), Raney nickel (40 g, water wet), and sodium hydroxide (4.00 g, 8 mol % aqueous) in a stirred reactor. The reactor was sealed and sparged with hydrogen. The reaction mixture was stirred for 13 h at 85° C. and then an additional 8 h at 100° C. The mixture was then filtered through a pad of Celite. The resulting solution was treated with Darco G-60 (35 g) and heated to reflux for 1 h, then cooled to ambient temperature and stirred an additional 3 h. This mixture was filtered through Celite (350 g), and the pad washed with EtOAc (1.5 L). The solvent was removed in vacuo and methyl tert-butyl ether (1 L) was added. This was heated for 15 min at 50° C., stirred for 1 h at ambient temperature, filtered, and the solvent removed in vacuo. Approximately half of the resulting crude solid was purified by chromatography on silica gel (gradient elution, 2-30% MeOH/CH2Cl2) to give 37 g of the title compound as a light brown solid. 1H NMR (300 MHz, CDCl3) δ 6.96 (t, J=7.6 Hz, 1H), 6.55 (dd, J=10.7, 7.6 Hz, 2H), 4.44-4.24 (m, 1H), 2.95-2.80 (m, 3H), 2.38 (dd, J=16.1, 7.6 Hz, 1H), 2.09-1.96 (m, 1H), 1.85-1.70 (m, 1H).

1. customThe reactor was sealed
2. customsparged with hydrogen
3. customan additional 8 h
4. customat 100° C
5. filtrationThe mixture was then filtered through a pad of Celite
6. additionThe resulting solution was treated with Darco
7. temperature(35 g) and heated
8. temperatureto reflux for 1 h
9. temperaturecooled to ambient temperature
10. stirringstirred an additional 3 h
11. filtrationThis mixture was filtered through Celite (350 g)
12. washthe pad washed with EtOAc (1.5 L)
13. customThe solvent was removed in vacuo and methyl tert-butyl ether (1 L)
14. additionwas added
15. temperatureThis was heated for 15 min at 50° C.
16. stirringstirred for 1 h at ambient temperature
17. filtrationfiltered
18. customthe solvent removed in vacuo
19. customApproximately half of the resulting crude solid was purified by chromatography on silica gel (gradient elution, 2-30% MeOH/CH2Cl2)

ORD record

ord-e188d7f802744bf198accf3b199657e3

Source dataset

uspto-grants-2013_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08609692B2