Enantioselective Synthesis of Tetrahydrocarbazoles through a Michael Addition/Ciamician-Plancher Rearrangement Sequence: Asymmetric Synthesis of a Potent Constrained Analogue of MS-245

Awakening an ancient rearrangement: A one‐pot sequential Friedel–Crafts‐type Michael addition/Ag+‐mediated Ciamician–Plancher rearrangement reaction on C2,C3‐nonsubstituted indoles can be used for accessing enantiomerically enriched pharmaceutically relevant 1,2,3,4‐tetrahydrocarbazoles. The methodology was applied in an enantioselective total synthesis of a highly potent serotonin 5‐HT6 receptor antagonist (see scheme).