反应详情

2,2,5-trimethyl-1,3-dioxan-4,6-dione II (17.4 g, 110 mmol), 4-acetoxy-azetidinone I (28.7 g, 100 mmol) and K2CO3 (15.2 g, 110 mmol) were mixed in dry acetonitrile (150 mL, KF=5.6 mg/mL), and the mixture was aged at 45-50° for 14 hours. Upon completion, the reaction mixture was cooled to room temperature and water (150 mL) was added. The organic layer was separated and the aqueous layer was back extracted with acetonitrile (100 mL). Combined organic extracts were washed with brine (100 mL) and concentrated to ca. 50 mL in volume. The mixture was then diluted with heptane (200 mL) and concentrated to 50 mL. Additional heptane (150 mL) was added and the mixture was aged at room temperature for crystallization. The resulting product was collected by filtration, washed with heptane (50 mL) and dried under vacuum at 40-50 for 15 hours to give an off-white crystalline solid (30.9 g, 80.2 mmol). A second crop was obtained by concentrating the combined filtrate and washed to ca. 50 mL in and aging at room temperature to give a white, fluffy solid (2.07 g, 5.4 mmol). Combined yield was 85.6%. Melting Range (° C.) 78-83 d.

1. customThe organic layer was separated
2. extractionthe aqueous layer was back extracted with acetonitrile (100 mL)
3. washCombined organic extracts were washed with brine (100 mL)
4. concentrationconcentrated to ca. 50 mL in volume
5. additionThe mixture was then diluted with heptane (200 mL)
6. concentrationconcentrated to 50 mL
7. additionAdditional heptane (150 mL) was added
8. customthe mixture was aged at room temperature for crystallization
9. filtrationThe resulting product was collected by filtration
10. washwashed with heptane (50 mL)
11. customdried under vacuum at 40-50 for 15 hours