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Following the general method of K. Wachi and A. Terada (Chem. Pharm. Bull., 1980, 28, 465-472), a mixture 81 mg (0.29 mmoles) of 3-(5-ethyl-2-pyridinyl)-2,2-dimethyl-2.3-dihydro-(4H)-1,3-benzoxazin-4-one and 2.0 mL of concentrated hydrochloric acid was heated to reflux for 8 h. The reaction was cooled to room temperature and the solvent was evaporated. The residue was dissolved in 4 mL ethyl acetate and washed with 3×1 mL of a 1:1 mixture of 10% of aqueous sodium hydroxide solution and saturated aqueous sodium chloride. The organic solution was dried (sodium sulfate), decanted, and evaporated to give 26 mg (84% yield) of 2-amino-5-ethylpyridine as an amber oil.

1. temperatureto reflux for 8 h
2. customthe solvent was evaporated
3. dissolutionThe residue was dissolved in 4 mL ethyl acetate
4. washwashed with 3×1 mL of a 1:1 mixture of 10% of aqueous sodium hydroxide solution and saturated aqueous sodium chloride
5. dry with materialThe organic solution was dried (sodium sulfate)
6. customdecanted
7. customevaporated