[OH:1][N:2]1[C:7]([CH3:9])([CH3:8])[CH2:6][C:5](=[O:10])[CH2:4][C:3]1([CH3:12])[CH3:11].[CH3:13]S(C)=O.OO>O>[CH3:13][O:1][N:2]1[C:7]([CH3:8])([CH3:9])[CH2:6][C:5](=[O:10])[CH2:4][C:3]1([CH3:12])[CH3:11]A 5.0 L 4 neck mechanically stirred flask is charged with 1oxyl-2,2,6,6-tetramethyl-4-piperidone (300 g, 1.76 moles), ferrous sulfate heptahydrate (513.7 g, 1.85 moles) and dimethylsulfoxide (1450 g). Hydrogen peroxide, 30% (279.2 g, 2.46 moles), is added over a 1 hour 45 min span. The temperature is maintained at 29-32° C. The content is stirred for an additional 30 min at 25-30° C. and then chilled below 1° C. Water (1250 ml) is added and the mixture is extracted with four 750 ml portions of ethyl acetate. The combined extracts are washed, 2×1.0 L of H2O, then 1×500 ml of saturated NaCl and then dried over anhydrous MgSO4. Ethyl acetate is evaporated and the product is distilled (82-84° C. 10.33×10−2 bar), yielding 254 g of a pale yellow oil (yield: 78% of theory; IR-spectrum: Ketone carbonyl, 1710 cm-1).
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