H 5 IO 6, as an Efficient Reagent for the Aromatization of Tetrahydro‐ β ‐carbolines: Total Synthesis of Norharman, Harmane, Harmine, Kumujian‐C, and Orthoscuticellines B

ABSTRACT A new method is reported for the synthesis of β ‐carbolines and their derivatives using H 5 IO 6 in DMSO solvent. The method is mild and efficient for oxidative decarboxylation and aromatization of tetrahydro β ‐carbolines (TH β C), resulting in good to excellent yields (70% to 88%) of β ‐carbolines. This protocol has further been utilized for the synthesis of β ‐carbolines based natural products, for examples, norharmane, harmane, harmine, Kumujian‐C, and Orthoscuticellines A and B.