Synthesis of Indolylquinolines, Indolylacridines, and Indolylcyclopenta[<i>b</i>]quinolines from the Baylis–Hillman Adducts: An in Situ [1,3]-Sigmatropic Rearrangement of an Indole Nucleus To Access Indolylacridines and Indolylcyclopenta[<i>b</i>]quinolines

A simple and easy route to the synthesis of a variety of structurally diverse indolylquinolines, indolylacridines, and indolylcyclopenta­[<i>b</i>]­quinoline derivatives via the reductive cyclization of C-alkylated indole derivatives, derived from acyclic as well as cyclic Baylis–Hillman adducts with indoles, is described. An unusual in situ [1,3]-sigmatropic rearrangement of the indole nucleus was observed during the reductive cyclicization of α-regioselective B–H adducts containing indoles to produce indolylacridines and indolylcyclopenta­[<i>b</i>]­quinoline derivatives.