Safe and easy route for the synthesis of 1,3-dimethyl-1,2,3-triazolium salt and investigation of its anticancer activities.

We have developed a new safe and easy route for the synthesis of 1,3-dimethyl-1,2,3-triazolium derivatives. We have reported the synthesis of 4,9-dioxo-1,3-dimethylnaphtho[2,3-d][1,2,3]triazol-3-ium chloride from methylation of 1-methyl-1H-naphtho[2,3-d][1,2,3]triazole-4,9-dione. The synthesis of 1-methyl-1H-naphtho[2,3-d][1,2,3]triazole-4,9-dione is inefficient as a significant amount of by-product is formed that is difficult to separate and also unsafe as it requires the use of hazardous methylazide as a starting material. It is, however, important to develop an improved method for the synthesis of 4,9-dioxo-1,3-dimethylnaphtho[2,3-d][1,2,3]triazol-3-ium salt due to its significant anticancer activities. Herein, we report a safe and convenient route for the synthesis of this compound, which lead to more detailed exploration of its profound anticancer activities. The improved method can be applicable for the synthesis of other 1,3-dimethyl-1,2,3-triazolium salts of interest without the use of potentially explosive methylazide. The compound synthesized in this new method shows significant anticancer activities against melanoma, colon cancer, non-small cell lung cancer and central nervous system (CNS) cancer with GI50 values ranging from low μM to nM.