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温度

0 °C

To a solution of 2,2-dimethyl-1,3-dioxane-4,6-dione (14.4 g, 0.1 mol) and pyridine (19.4 mL) in CH2Cl2 (150 mL) at 0° C., a solution of 3-methylbutyryl chloride (12 g, 0.1 mmol) in CH2Cl2 (140 mL) was added slowly. The reaction mixture was stirred for 1 h at 0° C. and for a further 1 h at rt. The mixture was concentrated to give a residue, which was diluted with EtOAc (500 mL) and filtered. The filtrate was washed with 10% aq Na2CO3 (200 mL) and water (200 mL). The combined aqueous layers were extracted with EtOAc (100 mL). The combined organic layers were washed with brine (100 mL), dried over MgSO4 and concentrated to give crude 5-(3-methylbutanoyl)-2,2-dimethyl-1,3-dioxane-4,6-dione (26 g), which was used in the next step without further purification.

1. concentrationThe mixture was concentrated
2. customto give a residue, which
3. filtrationfiltered
4. washThe filtrate was washed with 10% aq Na2CO3 (200 mL) and water (200 mL)
5. extractionThe combined aqueous layers were extracted with EtOAc (100 mL)
6. washThe combined organic layers were washed with brine (100 mL)
7. dry with materialdried over MgSO4
8. concentrationconcentrated