Ethylene Glycol → 4-Hydroxycarbazole

Temperature

120 °C

To a mixture of 1,2,3,9-tetrahydro-4H-carbazol-4-one (6.02 g, 32.5 mmol) in 1:1 ethylene glycol: p-dioxane (100 mL) at 80° C. is added copper (II) chloride (21 g, 156.2 mmol). The mixture is heated for 20 minutes. The mixture is then partitioned between water and ethyl acetate. The layers are separated and the organic layer is washed three times with water (200 mL). The organic layer is dried over anhydrous sodium sulfate, filtered, and concentrated. The residue is dissolved in DMF (100 mL) to which is added lithium bromide (7.04 g, 81.25 mmol) and lithium carbonate (6.0 g, 81.25 mmol). The mixture is heated at 120° C. for 4.5 hours. The mixture is then partitioned between water and ether. The ether layer is washed three times with water (200 mL). The ether layer is dried over anhydrous sodium sulfate, filtered and concentrated. Column chromatography, silica gel (800 mL), using CH2Cl2 as eluent gave 1.1 g (18%) of the title compound; 1H NMR (CDCl3) δ5.26, 6.57, 7.01, 7.26, 7.41, 8.05, 8.26; Anal. Calcd for C12H9NO: C, 78.67; H, 4.95; N, 7.64. Found: C, 78.04; H, 4.94; N, 7.58.

1. temperatureThe mixture is heated for 20 minutes
2. customThe mixture is then partitioned between water and ethyl acetate
3. customThe layers are separated
4. washthe organic layer is washed three times with water (200 mL)
5. dry with materialThe organic layer is dried over anhydrous sodium sulfate
6. filtrationfiltered
7. concentrationconcentrated
8. dissolutionThe residue is dissolved in DMF (100 mL) to which
9. customThe mixture is then partitioned between water and ether
10. washThe ether layer is washed three times with water (200 mL)
11. dry with materialThe ether layer is dried over anhydrous sodium sulfate
12. filtrationfiltered
13. concentrationconcentrated

ORD record

ord-c8e65610a98c4057991112db85ba2a4c

Source dataset

uspto-grants-2003_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06514968B1