[OH:1][C:2]1[CH:10]=[CH:9][CH:8]=[C:7]2[C:3]=1[CH:4]([CH3:13])[C:5](=[O:12])[N:6]2[CH3:11].[C:14](=O)([O-])[O-].[K+].[K+].COS(OC)(=O)=O>CC(C)=O>[CH3:14][O:1][C:2]1[CH:10]=[CH:9][CH:8]=[C:7]2[C:3]=1[CH:4]([CH3:13])[C:5](=[O:12])[N:6]2[CH3:11]A slurry of 1,3-dihydro-4-hydroxy-1,3-dimethyl-2H-indol-2-one (50 g), milled potassium carbonate (60.1 g) and HPLC grade acetone (400 ml) was mechanically stirred at room temperature as dimethylsulfate (41.4 ml) was added dropwise. The addition funnel was replaced with a condenser and the slurry was refluxed for 18 hours. The K2CO3 was filtered off and washed well with acetone. Acetone was evaporated and the residue was purified by column chromatography to yield 46.5 g of an oil. The oil was dissolved in ether and placed in the refrigerator where, upon standing overnight, the product crystallized, m.p. 73°-74° C.
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