Cyclization and N‑Iodosuccinimide-Induced Electrophilic Iodocyclization of 3‑Aza-1,5-enynes To Synthesize 1,2-Dihydropyridines and 3‑Iodo-1,2-dihydropyridines

Metal-free cyclization and N-iodosuccinimide-induced electrophilic iodocyclization of readily available 3-aza-1,5-enynes have been developed. The reactions selectively give 1,2-dihydropyridines and 3-iodo-1,2-dihydropyridines involving an aza-Claisen rearrangement and a 6π-electrocyclization step. Furthermore, the reaction could be carried out in 10 g scale for the synthesis of 1,2-dihydropyridines.本研究开发了以易得的3-氮杂-1,5-烯炔为底物的无金属环化反应，以及N-碘代丁二酰亚胺（N-iodosuccinimide）诱导的亲电碘代环化反应。两类反应均可高选择性地生成1,2-二氢吡啶与3-碘代-1,2-二氢吡啶，反应过程涉及氮杂克莱森重排（aza-Claisen rearrangement）与6π电环化（6π-electrocyclization）步骤。此外，该合成1,2-二氢吡啶的反应可放大至10克级规模。