Herrmann-Beller phosphapalladacycle-catalyzed addition of alkynes to norbornadienes

Herrmann−Beller (H−B) phosphapalladacycle selectively catalyzed the addition of terminal alkynes across one double bond of norbornadiene to afford exo-5-alkynyl-bicyclo[2.2.1]hept-2-enes. The reaction shows general applicability to various functionalized alkynes and bicyclo[2.2.1]hepta-2,5-dienes. Insights into the mechanism of this reaction are discussed.