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温度

0 °C

A suspension of dry magnesium chloride (0.471 g) in dichloromethane (6 ml) was treated with 4-tert-butoxy-3-oxo-butyric acid ethyl ester [1.00 g, Reference Example 43]. This mixture was cooled to 0° C., then treated with pyridine (0.80 ml), then stirred for 15 minutes at 0° C. and then treated with acetyl chloride (0.352 ml). After stirring for a further 15 minutes at 0° C. and then for 1 hour at ambient temperature the reaction mixture was treated with saturated aqueous ammonium chloride solution and then extracted twice with ethyl acetate. The combined extracts were dried over magnesium sulfate and then evaporated to yield 2-acetyl-4-tert-butoxy-3-oxo-butyric acid ethyl ester (1.15 g) as a yellow oil which was used without further purification. LC-MS (METHOD B): RT=3.16 minutes; 243 (M−H)−.

1. stirringAfter stirring for a further 15 minutes at 0° C.
2. extractionextracted twice with ethyl acetate
3. dry with materialThe combined extracts were dried over magnesium sulfate
4. customevaporated