2-Aminophenol → 3,4-Dihydro-2H-1,4-benzoxazine

Temperature

130 °C

To a solution of 2-aminophenol (8.01 g) in N,N-dimethylformamide (70 ml), potassium carbonate (51.0 g) and 1,2-dibromoethane (9.5 ml) were added and stirred at 130° C. for 7.5 hours and then at room temperature for 3 days. After addition of additional 1,2-dibromoethane (9.5 ml), the reaction mixture was stirred at 130° C. for 6 hours. The reaction mixture was diluted with ice-cold water and extracted with ethyl acetate, and the organic layer was dried over anhydrous sodium sulfate. After the desiccant was filtered off, the solvent was distilled off under reduced pressure and the resulting residue was purified by silica gel column chromatography (eluting solvent: n-hexane:ethyl acetate=20:1 to 5:1) to give the titled compound, i.e., 3,4-dihydro-2H-1,4-benzoxazine (3.77 g) as a brown oil.

1. waitat room temperature for 3 days
2. stirringthe reaction mixture was stirred at 130° C. for 6 hours
3. additionThe reaction mixture was diluted with ice-cold water
4. extractionextracted with ethyl acetate
5. dry with materialthe organic layer was dried over anhydrous sodium sulfate
6. filtrationAfter the desiccant was filtered off
7. distillationthe solvent was distilled off under reduced pressure
8. customthe resulting residue was purified by silica gel column chromatography (eluting solvent: n-hexane:ethyl acetate=20:1 to 5:1)

ORD record

ord-83006ffbd90d488ea5624925f778e16d

Source dataset

uspto-grants-2012_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08222417B2