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.

本研究对α-氨基丙二烯与β-氨基丙二烯分别与烯丙基卤化物的钯催化偶联环化反应进行了系统探究，该两类反应可分别生成3-烯丙基-2,5-二氢吡咯与1,2,3,6-四氢吡啶。所用起始原料易于获取。两类产物的核心骨架均通过化合物7i与9b的X射线衍射分析得以确证。通过考察2b分别与3-氯-1-丁烯、1-氯-2-丁烯及π-烯丙基钯物种的反应，以及(S)-2m与(R)-2n的偶联环化反应的立体化学结果，目前认为该转化过程大概率遵循Pd(II)催化路径，不过Pd(0)催化路径仍无法完全排除。