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...