DBU-promoted [3+2] cycloaddition for the synthesis of trispiro heterocycles from acetylpyrazolyl-substituted oxindoles and substituted isatins

Abstract

The stable and highly reactive 3-pyrazolyl oxindole derivatives have been developed as novel three-carbon synthons, which undergo a formal [3+2] annulation with isatin promoted by a non-nucleophilic base. This protocol provides a direct route for the rapid construction of a novel class of 3,3′-polyspiro oxindole-γ-butyrolactone scaffolds. These polyspiro frameworks are recognized as privileged scaffolds for a wide range of bioactive compounds. The developed protocol features mild reaction conditions, a broad substrate scope, and scalability.