Enantioselective Silver and Amine Co-catalyzed Desymmetrizing Cycloisomerization of Alkyne-Linked Cyclohexanones
作者:Rubén Manzano、Swarup Datta、Robert S. Paton、Darren J. Dixon
DOI:10.1002/anie.201612048
日期:2017.5.15
A silver(I) and amine co‐catalyzed desymmetrization of 4‐propargylamino cyclohexanones for the direct enantioselective synthesis of 2‐azabicyclo[3.3.1]nonanes is described. Exploiting reactivity arising from dual activation of the pendant terminal alkyne by silver(I) and the ketone moiety through transient enamine formation, this synthetically relevant transformation is easy to perform, efficient and
Enantioselective Total Synthesis of (−)-Himalensine A via a Palladium and 4-Hydroxyproline Co-catalyzed Desymmetrization of Vinyl-bromide-tethered Cyclohexanones
作者:Roman Kučera、Sam R. Ellis、Ken Yamazaki、Jack Hayward Cooke、Nikita Chekshin、Kirsten E. Christensen、Trevor A. Hamlin、Darren J. Dixon
DOI:10.1021/jacs.2c13710
日期:2023.3.8
providing access to molecular scaffolds found in a range of complex natural products. Following large-scale preparation of a key substrate and installation of a β-substituted enone moiety, the rapid construction of himalensine A was achieved using a highly convergent strategy based on an amide coupling/Michael addition/allylation/ring-closingmetathesis sequence which allowed the introduction of three of the
在此,我们通过 18 个步骤描述了 himalensine A 的收敛对映选择性全合成,通过钯/羟基脯氨酸共催化的乙烯基溴系环己酮的去对称化,通过高度对映和非对映选择性构建吗啡核来实现。密度泛函理论计算阐明了反应途径,它支持原位生成的烯胺中间体的分子内 Heck 反应,其中在决定速率和对映体的碳钯化步骤中,分子内羧酸盐与乙烯基钯物种的配位产生了精致的对映体选择性。该反应耐受不同的N-衍生物、全碳季铵中心和三取代烯烃,提供了在一系列复杂天然产物中发现的分子骨架的途径。在关键底物的大规模制备和 β-取代的烯酮部分的安装之后,使用基于酰胺偶联/迈克尔加成/烯丙基化/闭环复分解序列的高度收敛策略实现了 himalensine A 的快速构建,这允许仅在三个合成步骤中引入五个环中的三个(伸缩后)。此外,我们的策略为已知的四环后期中间体提供了一种新的对映选择性途径,该中间体以前曾用于合成许多溞叶生物碱。