OO.[CH3:3][C:4]1[N:9]=[CH:8][C:7]([CH2:10][N:11]=[N+:12]=[N-:13])=[CH:6][CH:5]=1.C1(=O)OC(=[O:18])C=C1.C(=O)([O-])O.[Na+]>C(Cl)Cl>[N:11]([CH2:10][C:7]1[CH:6]=[CH:5][C:4]([CH3:3])=[N+:9]([O-:18])[CH:8]=1)=[N+:12]=[N-:13]
After adding 30% aqueous hydrogen peroxide (7.5 ml, 6.6 mmol) dropwise to a solution of (6-methyl-3-pyridyl)methyl azide (8.9 g, 6.0 mmol) and maleic anhydride (6.5 g, 6.6 mmol) in methylene chloride (90 ml) over a period of 5 minutes while cooling on ice, the mixture was stirred at room temperature for 16 hours. Maleic anhydride (3.25 g) and 30% aqueous hydrogen peroxide (3.75 ml) were added in a similar manner while cooling on ice, and the mixture was stirred at room temperature for 4 hours. Saturated aqueous sodium hydrogencarbonate (100 ml) was added to the reaction mixture, NaHCO3 was further added to be basic, and extraction was performed with methylene chloride. The extract was washed with a brine and dried over anhydrous magnesium sulfate, and the solvent was distilled off to yield crude 5-(azidomethyl)-2-methyl-1-pyridiniumolate (7.45 g). This was used without further purification for the following reaction.
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