C[O-].[Na+].C[C:5](C)(C([O-])=O)[C:6]([O-])=[O:7].[C:13]1(=[C:19](C#N)[C:20]([NH2:22])=[O:21])[CH2:18][CH2:17][CH2:16][CH2:15][CH2:14]1.[OH-].[Na+]>CO>[O:7]=[C:6]1[NH:22][C:20](=[O:21])[CH2:19][C:13]2([CH2:14][CH2:15][CH2:16][CH2:17][CH2:18]2)[CH2:5]1
204 ml of a 5.4 M solution of sodium methylate in methanol, 550 ml methanol and 145.5 g of dimethylmalonate are placed in a 2 litre flask equipped with a mechanical stirrer, thermometer and condenser, under nitrogen flow. After 30 minutes, 148 g of cyclohexylidenecyanoacetamide are added over a period of 30 minutes. The mixture is left under agitation for 1.5 hours at 30° C., after which 626 g of 15% NaOH are added, then heated under reflux for 1.5 hours. 400 ml of methanol are distilled and the mixture is acidified with 36% HCl to pH 3 then heated under reflux for 3 hours. By cooling to 25° C. a precipitate is formed which is filtered off, washed with water until the washing waters are neutral and dried under vacuum at 45° C. 69 g of 2,4-dioxo-3-azaspiro[5,5]undecane are obtained.
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