Synthesis of 6-Methylindole-4,7-quinone and Anti-tumor Activities of Its Related Indolequinones

We synthesized 6-methylindole-4,5-quinone (1b) in order to clarify the structure of natural product, 5-methylindole-4,5-quinone (la) isolated from Drupella fragum. The synthesis features the construction of the indole ring based on an electrocyclic reaction of a 3-alkenyl-2-propargylpyrrole intermediate. Two synthetic methylindolequinones and their related compounds were examined in human lung cancer cell line NCI-H460 and human breast cancer cell line MDA-MB-231.