Cyclic Enecarbamates as Precursors of α,β-Unsaturated Iminium Ions: Reactivity and Synthesis of 6,6-Spirocyclic Ring Systems
作者:Zhanwei Wang、Niels Krogsgaard-Larsen、Benjamin Daniels、Daniel. P. Furkert、Margaret A. Brimble
DOI:10.1021/acs.joc.6b01343
日期:2016.11.4
β-unsaturated N-acyl iminium ions as dienophiles in Diels–Alder reactions and electrophilic alkylating agents are described. In the presence of Lewis and Brønsted acids, iminium precursor 22a underwent efficient Diels–Alder cycloaddition with a range of simple and complex dienes, culminating in the synthesis of 6,6-spirocyclic ring systems possessing the same relative stereochemistry as the spirocyclic imine
报道了环状烯甲酸酯的可扩展合成及其作为α,β-不饱和N-酰基亚胺鎓离子的便利前体的用途。新开发的路线克服了以前报道的方法中的合成和反应困难,易于扩大规模,并在需要时通过适合长期保存的稳定中间体进行生产。初步探讨了探索环状α,β-不饱和N-酰基亚胺鎓离子作为Diels-Alder反应中的亲二烯体和亲电烷基化剂的反应性。在路易斯酸和布朗斯台德酸的存在下,亚胺鎓前体22a进行了有效的Diels-Alder环加成反应以及一系列简单和复杂的二烯,最终合成了与海洋天然产物Gymnodimine 1中存在的螺环亚胺相同的相对立体化学的6,6-螺环系统。