Rapid synthesis of azepinoindole derivatives from tryptamine sulfonamides and bromoallyl sulfones via an acid-mediated cyclization and rearrangement.
Ravikumar Gurram, Jagadeesh Babu Nanubolu, Rajeev S Menon
Chemical Communications 2021 DOI: 10.1039/d0cc06991d (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Theoretical or philosophical paper Peer reviewed |
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| Key points | Reports a novel acid-promoted cyclization-rearrangement that converts tryptamine-derived N-sulfonyl enamines into the azepinoindole framework found in subincanadine F, ibogaine, and catharanthine. The enamines are prepared via a cesium carbonate-mediated formal vinylic substitution of 2-bromoallyl sulfones with tryptamine sulfonamides, and the authors state that the steric bulk of the N-sulfonyl group influences the reaction outcome. |
Abstract
The azepinoindole framework present in natural alkaloids such as subincanadine F, ibogaine and catharanthine was formed in a novel acid-promoted cyclization-rearrangement of tryptamine-derived N-sulfonyl enamines. The latter were conveniently prepared via a cesium carbonate mediated formal vinylic substitution reaction of 2-bromoallyl sulfones (allenyl sulfone surrogate) and tryptamine sulfonamides. The azepinoindole forming cyclization-rearrangement involves the initial generation of a six-membered tetrahydro-β-carboline derivative. The steric bulk of the N-sulfonyl group on tryptamine plays an important role in deciding the reaction outcome.