O-Methylhydroxylamine → 1-(2-methyl-[1,3]dioxan-2-yl)propane-1,2-dione bis(O-methyloxime)

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Reaction Steps

239 g (0.4 mol) of 14% strength methanolic methoxyamine solution, 50 g (0.6 mol) of sodium acetate (anhydrous), dissolved in 250 ml of methanol, 75 g of magnesium sulfate and 92 g of the ketal (Example 3), dissolved in 100 ml of methanol, were initially charged at room temperature. The pH meter showed a value of 6. The mixture was stirred for 10 minutes, during which the pH decreased to 5.2, and a pH of 4.2 was set by dropwise addition of sodium acetate. The mixture was stirred at room temperature for another 20 hours and the conversion was monitored by HPLC. 7% of starting material was left. After a further 4 hours of stirring, the reaction mixture was neutralized using dilute aqueous sodium hydroxide solution and diluted with water. The mixture was extracted with methyl tert-butyl ether. The combined organic phases were washed with dilute ammonium chloride solution, dried over magnesium sulfate and concentrated. This gave 92 g (89% yield) of the title compound.

Provenance & Evidence