Studies on Pd(II)-Catalyzed Coupling−Cyclization of α- or β-Amino Allenes with Allylic Halides

The palladium-catalyzed coupling−cyclization of α- or β-amino allenes with allylic halides leading
to 3-allylic 2,5-dihydropyrroles and 1,2,3,6-tetrahydropyridines, respectively, was studied. The
starting materials are easily available. The skeletons of both two classes of products were established
by the X-ray diffraction studies of 7i and 9b. Through the study of the reaction of 2b with 3-chloro-1-butene, 1-chloro-2-butene, and π-allyl palladium species and the stereochemical outcome of the
coupling cyclization of (S)-2m and (R)-2n, it is believed that the current transformation most likely
proceeded via a Pd(II)-catalyzed pathway, although a Pd(0) pathway cannot be completely excluded.