Stereoselective Synthesis of Functionalized Indenes via Regioselective Cascade Iodoalkylation of Alkynes.

Herein, an unprecedented and modular strategy for the stereoselective construction of functionalized indene scaffolds has been developed via a base-promoted, regioselective cascade iodoalkylation of alkynes. Michael addition of methanol to the carbon-carbon double bond initiated the consecutive formation of C-O, C-C, and C-I bonds in a single operation. The product features an exocyclic double bond and versatile functional groups (-CN, -COOEt, -I, -OMe), offering scope for transformation into biologically active pharmacophores. Notably, postfunctionalization of the resulting indene via decarboxylative protodeiodination in the presence of N-centered nucleophiles demonstrates the broad synthetic applicability of this protocol, enabling the metal-free construction of challenging C-N bonds and access to amine- and indole-substituted benzofulvenes.