反应详情

11 g of methyl orthoformate and 20 ml of acetic anhydride were added to 8.3 g of 1-ethylpiperidine-2,4-dione, and they were refluxed for 7 hours and then allowed to cool. Excessive methyl orthoformate and acetic anhydride were removed by vacuum distillation. The resulting brown reside was subjected to vacuum distillation (0.5 mmHg, bath temperature of 200° to 250° C.) using a kugelrohr apparatus, whereby 2.7 g of 1-ethyl-3-methoxymethylenepiperidine-2,4-dione was obtained as a crystal with an yield of 25%. This crystal was recrystallized from a mixed solvent consisting of ethyl acetate and hexane to obtain a needle-like crystal of said compound.

1. temperaturewere refluxed for 7 hours
2. temperatureto cool
3. customExcessive methyl orthoformate and acetic anhydride were removed by vacuum distillation
4. distillationThe resulting brown reside was subjected to vacuum distillation (0.5 mmHg, bath temperature of 200° to 250° C.)