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).