反应详情

Trifluoroacetic acid (10 mL) was added to a dichloromethane solution of the compound obtained in Example 23 (5.7 g, 14 mmol), and the mixture was stirred at room temperature overnight. The solvents were distilled off, and the residue was purified by silica gel column chromatography (hexane:ethyl acetate=3:2), to give a free compound. Thereafter, 4 mol/L hydrogen chloride-dioxane (8.0 mL, 32 mmol) was added thereto, and the mixture was stirred for 1 hour. The solvents were distilled off under a reduced pressure, and ether was added to the residue to allow crystallization. The precipitated crystals were separated by filtration and dried, to give 4.1 g (69%) of the captioned compound.

1. distillationThe solvents were distilled off
2. customthe residue was purified by silica gel column chromatography (hexane:ethyl acetate=3:2)
3. customto give a free compound
4. stirringthe mixture was stirred for 1 hour
5. distillationThe solvents were distilled off under a reduced pressure, and ether
6. additionwas added to the residue
7. customcrystallization
8. customThe precipitated crystals were separated by filtration
9. customdried