A Diversity-Oriented Approach to Spiroindolines: Post-Ugi Gold-Catalyzed Diastereoselective Domino Cyclization

摘要

Gold-catalyzed carbocyclization and heteroannulation strategies have recently attracted much attention owing to the selective and efficient activation of the C≡C bond towards a wide range of nucleophiles that these methods provide. Domino approaches involving gold-catalysis lead to complex heterocyclic compounds under exceedingly mild reaction conditions. Although gold-catalyzed approaches are rising to prominence, they suffer in terms of diversity and procedural length. Multistep sequences are usually required for assembling the starting material for cyclization. We have recently reported a concise route to indoloazocines by a sequential Ugi/gold-catalyzed intramolecular hydroaryla-tion approach. Inspired by these findings and as a result of our continued synthetic interest in the indole core, multi-component reactions and transition metal-catalysis, we have developed a post-Ugi gold-catalyzed domino cyclization method to generate spiroindolines.