Highly regioselective synthesis of N-acyl-2,3-dihydropyrrole or N-sulfonyl-2,3-dihydropyrrole derivatives by nano-palladium catalyzed cycloisomerization of 1,6-dienes

Porous palladium nanoparticles were prepared using a solution-phase approach. Their structures and shapes were analyzed by XRD, EDS, TEM and HRTEM. These palladium nanoparticles were used to catalyze the cycloisomerization reaction of N,N-diallylamide or N,N-diallylsulfonamide, and N-acyl-2,3-dihydropyrrole or N-sulfonyl-2,3-dihydropyrrole derivatives were therefore synthesized with very high regioselectivity and in good yields. The nano-palladium catalyst showed high efficiency and it can be reused several times. A hydropalladation mechanism was proposed for this reaction.