Divergent synthesis of alkylphosphonate-containing indanes and indenes <i>via</i> norbornene derivative-controlled palladium-catalyzed three-component systems

A palladium-catalyzed divergent three-component reaction employing norbornene derivatives as controlled switches toward phosphonate-containing indenes and indanes was established. When using norbornadiene, norbornene or 7-oxabenzonorbornadiene as a substrate, alkylphosphonate-containing indanes were synthesized through a cascade [3+2] cyclization and alkylation of P(O)H process. Alternatively, oxanorbornadiene enabled the assembly of phosphonate-containing indenes <i>via</i> a subsequent retro-Diels-Alder reaction. Moreover, this strategy provides a new platform for the rapid construction of bis-alkylphosphonate functionalized diindane scaffolds.