1-Ethylpiperidine-2,4-dione → 1-Ethyl-3-methoxymethylenepiperidine-2,4-dione
Reaction equation
[CH2:1]([N:3]1[CH2:8][CH2:7][C:6](=[O:9])[CH2:5][C:4]1=[O:10])[CH3:2].[CH:11]([O-])([O-])[O:12][CH3:13]>C(OC(=O)C)(=O)C>[CH2:1]([N:3]1[CH2:8][CH2:7][C:6](=[O:9])[C:5](=[CH:11][O:12][CH3:13])[C:4]1=[O:10])[CH3:2]Participants
4
Reactant 2
Product 1
Reagents, catalysts & solvents 1
Procedure
Added to 8.3 g of 1-ethylpiperidine-2,4-dione were 11 g of methyl orthoformate and 20 ml of acetic anhydride. The resultant mixture was refluxed for 7 hours. After allowing the reaction mixture to cool down, excess methyl orthoformate and acetic anydride were distilled off under reduced pressure. The brown residue was distilled under reduced pressure in a Kugelroll apparatus (0.5 mmHg; bath temperature: 200°-250° C.) to obtain 2.7 g of 1-ethyl-3-methoxymethylenepiperidine-2,4-dione as crystals (yield: 25%). The crystals were recrystallized from a mixed solvent of ethyl acetate and hexane to obtain needles.