反应详情

Under an argon atmosphere, to a solution of tert-butyl (5-methoxy-2-methylphenyl)carbamate (1.42 g) in tetrahydrofuran (30 mL) was slowly added dropwise sec-butyllithium (1.06 mol/L hexane-cyclohexane solution, 12.5 mL) at −40° C., and the mixture was stirred for 15 minutes. Then, a solution of 2-methylpropionaldehyde (476 mg) in tetrahydrofuran (3 mL) was added dropwise thereto, and the mixture was stirred at −40° C. for 15 minutes, and then stirred at room temperature for additional 40 minutes. To the reaction mixture was added a saturated aqueous ammonium chloride solution, followed by extraction with ethyl acetate. The organic layer was washed with saturated brine, dried over anhydrous magnesium sulfate, and then concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluting solvent: ethyl acetate-hexane) to obtain the title compound (929 mg). 1H-NMR (CDCl3) δ ppm: 0.96-1.06 (6H, m), 1.52 (9H, s), 1.70-1.83 (1H, m), 1.90 (1H, d, J=3.8 Hz), 2.57-2.75 (2H, m), 3.48-3.59 (1H, m), 3.80 (3H, s), 6.59 (1H, dd, J=2.8, 8.5 Hz), 7.00 (1H, d, J=8.5 Hz), 7.43 (1H, br s), 7.91 (1H, br s).

1. stirringthe mixture was stirred at −40° C. for 15 minutes
2. stirringstirred at room temperature for additional 40 minutes
3. extractionfollowed by extraction with ethyl acetate
4. washThe organic layer was washed with saturated brine
5. dry with materialdried over anhydrous magnesium sulfate
6. concentrationconcentrated under reduced pressure
7. customThe residue was purified by silica gel column chromatography (eluting solvent: ethyl acetate-hexane)