Synthesis of pyrrolophenanthridone alkaloid kalbretorine from indolecarboxylic acids via hypervalent iodine(III) mediated halodecarboxylation and reduction

The treatment of 8,9,10-trimethoxy-7H-pyrrolo[3,2,1-de]phenanthridine-4,5-dicarboxylic acid with phenyliodine diacetate and potassium iodide in tetrahydrofuran gave the corresponding 4,5-diiodo derivative, which was converted to kalbretorine via reduction, demethylation, followed by alkylation.