4-Amino-3-iodo-N-methylbenzenemethanesulfonamide is an intermediate in synthesizing 1-(3-(2-(Dimethylamino)ethyl)-1-((5-((N-methylsulfamoyl)methyl)-1H-indol-3-yl)methyl)-1H-indol-5-yl)-N-methylmethanesulfonamide (D471500), an impurity of Sumatriptan (S810000, Succinate Salt); a serotonin 5HT1-receptor agonist.