Phosphetes via Transition Metal Free Ring Closure - Taking the Proper Turn at a Thermodynamic Crossing

A transition metal free route to phosphetes featuring an exocyclic alkene unit is presented. In this approach phosphanides are added to a variety of diynes generating phosphaallylic intermediates which depending on the reaction conditions transform either to phosphetes or the corresponding phospholes. Investigation of the reaction mechanism by combined quantum chemical and experimental means identifies phosphole formation as thermodynamically controlled reaction path, whereas kinetic control furnishes the corresponding phosphetes. Structural and luminescence properties of the rare class of phosphetes are explored, as well as for selected key intermediates.

Automated summary

A transition metal-free route to phosphetes with an exocyclic alkene unit is proposed, where phosphanides are added to diynes to form phosphaallylic intermediates that can transform into phosphetes or phospholes depending on reaction conditions. The study suggests that phosphole formation is thermodynamically controlled, while kinetic control leads to the formation of phosphetes. Structural and luminescence properties of the rare class of phosphetes and key intermediates are investigated.