C(Cl)(=O)C(Cl)=O.[NH2:7][C:8]1[CH:20]=[CH:19][CH:18]=[CH:17][C:9]=1[CH2:10][S:11]([N:14]([CH3:16])[CH3:15])(=[O:13])=[O:12].[CH3:21][N:22]([CH:24]=O)[CH3:23]>>[CH3:21][N:22]([CH:24]=[N:7][C:8]1[CH:20]=[CH:19][CH:18]=[CH:17][C:9]=1[CH2:10][S:11]([N:14]([CH3:16])[CH3:15])(=[O:13])=[O:12])[CH3:23]Dimethylformamide (20 ml) was cooled under a nitrogen atmosphere to −40° C. in a dry ice-acetonitrile bath. Oxalyl chloride (2 ml) was added dropwise at such a rate as to maintain the temperature below −30° C. Upon completion of the addition, the suspension was allowed to rise to room temperature. After about an hour, 2-aminobenzyl-N,N-dimethylsulfonamide (0.630 g) dissolved in DMF (5 ml) was added with stirring and the reaction mixture was stirred at room temperature for 4 h. The solution was partitioned between 1% sodium hydroxide solution and ethyl acetate. The organic layer was dried over magnesium sulfate, filtered and evaporated to dryness to afford C-[2-(dimethylamino-methyleneamino)-phenyl]-N,N-dimethyl-methanesulfonamide as an oil which was used directly in the next step.
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