Diastereoselective Synthesis of Cyclopenta[]chromanones via Pd-Catalyzed [3+2] Cycloaddition.

A straightforward method for synthesizing cyclopenta[]chromanones is demonstrated. The strategy involves a [3+2] cycloaddition of VCPs and activated coumarins under Pd-catalyzed conditions. The reaction provides the desired products bearing up to four consecutive stereocenters with high diastereocontrol.

Organophosphorus-Catalyzed Borylative Ring-Opening of Vinylcyclopropanes: A Stereoselective Route to δ-Valerolactones.

We report an operationally simple route to δ-valerolactones through an organophosphorus-catalyzed borylative ring-opening/allylation of vinylcyclopropanes providing δ-hydroxy esters stereoselectively. The δ-hydroxy esters were lactonized to obtain densely substituted δ-valerolactones. The present methodology exhibited enhanced functional group tolerance compared to the existing metal-mediated methods.