Stereoselective Synthesis of Functionalized Indenes via Regioselective Cascade Iodoalkylation of Alkynes

J Org Chem. 2025 Jul 11;90(27):9559-9575. doi: 10.1021/acs.joc.5c01020. Epub 2025 Jun 27.

Abstract

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.