Synthesis of 3-spirooxindole 3H-indoles through Rh(iii)-catalyzed [4+1] redox-neutral spirocyclization of N-aryl amidines with diazo oxindoles

In this paper, an efficient synthesis of 3-spirooxindole 3H-indoles through the coupling and spirocyclization of N-aryl amidines with diazo oxindoles is presented. Mechanistically, the formation of the title products involves a cascade process including Rh(iii)-catalyzed C(sp(2))-H bond cleavage, Rh-carbene formation and migratory insertion, intramolecular nucleophilic addition and ammonia elimination. In general, this novel spirocyclization features easily accessible substrates with a broad scope and generality, redox neutral reaction conditions, formation of multiple bonds with high efficiency, and structurally and pharmaceutically attractive products.

Automated summary

This paper presents an efficient method for the synthesis of 3-spirooxindole 3H-indoles through the coupling and spirocyclization of N-aryl amidines with diazo oxindoles. The mechanistic pathway involves a cascade process with easily accessible substrates, redox neutral conditions, high efficiency in forming multiple bonds, and attractive products in terms of structure and pharmaceutical properties.