Tandem Nucleophilic Addition/Oxy-2-azonia-Cope Rearrangement for the Formation of Homoallylic Amides and Lactams: Total Synthesis and Structural Verification of Motuporamine G
作者:Lijun Zhou、Zhiming Li、Yue Zou、Quanrui Wang、Italo A. Sanhueza、Franziska Schoenebeck、Andreas Goeke
DOI:10.1021/ja310002m
日期:2012.12.12
oxy-2-azonia-Cope rearrangements give homoallylic amides. In the case of 2-vinylcycloalkanones, the process results in ring enlargement, providing a novel route to 9- to 16-membered lactams. The preparative significance of this protocol was evidenced by a short synthesis of macrocyclic alkaloid motuporamine G. The stereochemistry-defining step of this oxy-azonia-Cope rearrangement was further studied
在路易斯酸的存在下,β,γ-不饱和酮和肟或亚胺进行亲核加成以产生两性离子中间体,随后的氧-2-偶氮-科普重排得到高烯丙基酰胺。在 2-乙烯基环烷酮的情况下,该过程导致环扩大,为 9 至 16 元内酰胺提供了一条新途径。该协议的制备意义由大环生物碱莫托泊明 G 的短合成证明。此 oxy-azonia-Cope 重排的立体化学定义步骤进一步计算研究。尽管在两性离子中间体的形成过程中存在高能预平衡,但 [3,3]-σ 步骤是决定速率和产物的步骤。椅子状过渡状态通常比船状过渡状态更受欢迎。