Electrophilic Cyclization of 2-Aminophenylprop-1-yn-3-ols into 3-Iodo-6-(aryldiazenyl)quinolines by Using a One-Pot Azo-Coupling and Iodocyclization Sequence

Abstract

6-(Aryldiazenyl)-3-iodoquinolines were prepared from readily available 2-aminoaryl propargyl alcohols, aryldiazonium salts, and molecular iodine. This three-component one-pot process proceeded through sequential azo-coupling, regioselective iodocyclization, and aromatization reactions to yield the corresponding quinoline derivatives. In the absence of iodine, Ca(OTf)2 was used to promote the azo-coupling and azacyclization reactions, which furnished the respective 6-aryldiazenylquinolines. In addition, 2-aminoaryl propargyl alcohols successfully underwent a regioselective intramolecular cyclization in the presence of Ca(OTf)2 to give 2,4-disubstituted quinolines. Cross-coupling reactions of the iodoquinolines were also performed without any effect to the diazo functionality.