Gold-catalyzed dual annulation of azide-tethered alkynes with nitriles: expeditious synthesis of oxazolo[4,5-c]quinolines

Abstract

A gold-catalyzed dual annulation of azide-tethered internal alkynes with nitriles has been developed for the synthesis of oxazolo[4,5-c]quinolines in good to high yields under mild and neutral reaction conditions. Mechanistic studies indicate that this reaction is initiated by a gold-catalyzed 6-endo-dig azide-yne cyclization, followed by a [3 + 2] cycloaddition with external nitriles. In addition, the utility of the current method is illustrated by the synthesis of useful polyfunctionalized quinoline derivatives, including 3-aminoquinolin-4(1H)-one and 3-hydroxyquinolin-4(1H)-one.