Synthesis of (2-(Quinolin-2-yl)phenyl)carbamates by a One-Pot Friedel–Crafts Reaction/Oxidative Umpolung Aza-Grob Fragmentation Sequence

Utilizing the easily available isatin-based propargyl amines prepared from isatins, terminal alkynes, and anilines, (2-(quinolin-2-yl)­phenyl)­carbamates were prepared by a one-pot reaction in sequence, combining the gold-catalyzed Friedel–Crafts cyclization, oxidative umpolung aza-Grob fragmentation, and nucleophilic addition. In this process, gold-catalyzed cyclization of isatin-based propargyl amines gave 1′H-spiro­[indoline-3,2′-quinolin]-2-ones, which were oxidized in situ by hypervalent iodine via the aza-Grob fragmentation to afford isocyano intermediates 2-(2-isocyanatophenyl)­quinolines. Followed by the nucleophilic addition with alcohol solvents, (2-(quinolin-2-yl)­phenyl)­carbamates were synthesized. This procedure features easy operation, a wide substrate scope, and mild conditions.