Ligand-Induced Acceleration of the Intramolecular [3 + 2] Cycloaddition between Alkynes and Alkylidenecyclopropanes

[chemical reaction: see text]. Bulky phosphite L6 and several sterically robust phosphoramidites are excellent ligands for promoting the Pd-catalyzed [3 + 2] intramolecular cycloaddition between alkylidenecyclopropanes and alkynes. The use of these ligands allows for low catalyst loadings and facilitates the otherwise sluggish cycloaddition of hept-6-ynylidenecyclopropane systems.