An Expeditious Benzannulation Reaction of Indol-3-yl-but-3-yn-2-ols to Substituted 2-Iodocarbazoles via Domino 5-endo Spirocyclization/Selective Vinyl Shift and Aromatization

Abstract

Regioselective benzannulation reaction of indol-3-yl-but-3-yn-2-ols to functionaly embellished 2-iodocarbazoles is described for the first time using iodine at room temperature in an open flask. This reaction proceeds through a cascade of 5-endo spirocyclization, ring-rearrangement through a vinyl shift, and aromatization in a short time. This protocol offers direct access to uncovered 2-iodocarbazoles, with a broad substrate scope and good to moderate yields. Further, we have demonstrated the synthetic potential of these compounds using cross-coupling reactions.