1 research outputs found
Brønsted Acid Mediated Alkenylation and Copper-Catalyzed Aerobic Oxidative Ring Expansion/Intramolecular Electrophilic Substitution of Indoles with Propargyl Alcohols: A Novel One-Pot Approach to Cyclopenta[<i>c</i>]quinolines
Copper-catalyzed oxidative ring-expansion/intramolecular
electrophilic
substitution of 3-dienylindoles leading to cyclopenta[<i>c</i>]quinolines and 3-indenylindoles under aerobic
conditions is described. The precursors, 3-dienylindoles, are formed
via Friedel–Crafts alkenylation followed by isomerization reactions
of 2-substituted indoles with tertiary propargyl alcohols under Brønsted
acid mediation. The methyl (sp<sup>3</sup>-C) group present in the
propargyl alcohol becomes a part of a six-membered ring in the final
ring-expansion products, the cyclopenta[<i>c</i>]quinolines
which are fluorescence active. Based on these observations, a novel
one-pot strategy for ring expansion from indole to cyclopenta[<i>c</i>]quinoline is discovered