A mixture of nitroisatin 31 (10 g, 0.052 mol), MeI (16.21 ml, 0.260 mol) and K2CO3 (21.56 g, 1.56 mol) in anhydrous DMF was stirred overnight at room temperature. Water was added to the reaction mixture and acidified with dilute HCl till acidic to pH paper. A yellow solid separated, 1-Methyl-5-nitroisatin was filtered and washed thoroughly with water till neutral to pH paper and air dried to a constant weight (9.66 g).
