反应详情

Step AAH (1): Concentrated sulfuric acid (0.200 mL, 3.75 mmol) was added to a mixture of 5-oxo-5-phenylpentanoic acid (4.0 g, 20.81 mmol), ethylene glycol (6.96 mL, 125 mmol), and trimethylorthoformate (6.90 mL, 62.4 mmol) in dichloromethane (40 mL) at it under nitrogen. The mixture was stirred at it for 16 h. Solid NaHCO3 (2.0 g) was carefully added. The resulting mixture was concentrated in vacuo. The residue was taken up in methanol (50 mL) and the vessel was placed in a it water bath. Aqueous 50% NaOH (5 mL) was slowly added and the mixture was stirred at for 16 h. The mixture was concentrated in vacuo (to remove methanol) and the resulting aqueous layer was neutralized to pH 2. The aqueous layer was extracted with EtOAc. The organic layer was dried over Na2SO4, filtered and concentrated in vacuo. The residue was crystallized from diethyl ether to afford 4-(2-phenyl-1,3-dioxolan-2-yl)butanoic acid (850 mg, 17% yield) which was contained with a significant portion of 5-oxo-5-phenylpentanoic acid. LC-MS (M+H)+ 235.1.

1. concentrationThe resulting mixture was concentrated in vacuo
2. additionAqueous 50% NaOH (5 mL) was slowly added
3. stirringthe mixture was stirred at for 16 h
4. concentrationThe mixture was concentrated in vacuo (to remove methanol)
5. extractionThe aqueous layer was extracted with EtOAc
6. dry with materialThe organic layer was dried over Na2SO4
7. filtrationfiltered
8. concentrationconcentrated in vacuo
9. customThe residue was crystallized from diethyl ether