合成路线1

The intermediate 2-[3-(benzylsulfonamido)-6-methyl-2-oxo-1,2-dihydropyridin-1-yl]acetic acid (VI) has been obtained as follows: The reaction of 2-hydroxy-6-methylpyridine-3-carboxylic acid (IX) with diphenylphosphoryl azide (DPPA), triethylamine and benzyl alcohol in refluxing dioxane gives 3-(benzyloxycarbonylamino)-6-methylpyridin-2(1H)-one (X), which is condensed with tert-butyl bromoacetate (II) by means of NaH in THF yielding the expected condensation product (XI). The deprotection od the amino group of (XI) with H2 over Pd/C in ethanol/water gives the aminopyridone (XII), which is acylated with benzylsulfonylchloride (XIII) in pyridine yielding the sulfonamide (XIV). Finally, the tert-butyl ester group of (XIV) is hydrolyzed with HCl in ethyl acetate to afford the target intermediate (VI).