Dimerization of a 3-Substituted Oxindole at C-3 and Its Application to the Synthesis of (.+-.)-Folicanthine
摘要:
The dimerization of an oxindole in good yield at C-3 to form a benzylic quaternary carbon-carbon bond is described. A radical anion chain mechanism is proposed for the reaction. The dimeric product is transformed into (+/-)-folicanthine by a series of reductions. A crystalline bis-borane complex of (+/-)-folicanthine was obtained, and its molecular structure was determined by X-ray crystallography.
Total Synthesis of (−)-Calycanthine via Iron-Catalyzed Stereoselective Oxidative Dimerization
作者:Leiyang Bai、Yinhao Ma、Xuefeng Jiang
DOI:10.1021/jacs.1c10498
日期:2021.12.15
Dimeric cyclotryptaminealkaloids typically feature vicinalall-carbonquaternarystereocenters and four nitrogen atoms. In comparison with the actual biosynthetic tryptophan derivatives, we designed the 2N-featured monomer 7, aiming to construct vicinalall-carbonquaternarystereocenters via a one-step dimerization process to access the 4N-featured isomeric members of this family. In this work, we
Direct access: Sterically hindered vicinal quaternary carbon stereocenters were constructed by catalytic enantio‐ and diastereoselective doubleMichaelreaction, providing straightforward access to dimeric hexahydropyrroloindole alkaloids. A Mn(4‐fluorobenzoate)2/Schiff base complex and a Mg(OAc)2/benzoic acid system were used as catalysts.
Naturally occurring bis(cyclotryptamine) alkaloids feature vicinal all-carbon quaternary stereocenters with an elongated labile C-3a–C-3a′ Sigma bond with impressive biological activities. In this report, we have developed a thio-urea catalyzed one-pot sequential Michael addition of bis-oxindole onto selenone to access enantioenriched dimeric 2-oxindoles with vicinal quaternary stereogenic centers
天然存在的双(环色胺)生物碱具有邻位全碳四元立体中心,具有延长的不稳定 C-3a–C-3a' Sigma 键,具有令人印象深刻的生物活性。在本报告中,我们开发了一种硫脲催化的一锅连续迈克尔加成双羟吲哚到硒酮上,以在假苄基位置获得具有邻位季立体中心的对映体富集的二聚体 2-羟吲哚(高达 96% ee 和 >20: 1博士)。该策略已成功应用于菊花碱、叶黄素和花蕊碱的对映异构体的全合成。
Copper catalyzed sequential arylation−oxidative dimerization of o-haloanilides: synthesis of dimeric HPI alkaloids
In this paper, we report a copper catalyzed sequential arylation-oxidative dimerization reaction as the key step for the synthesis of hexahydropyrroloindole alkaloids (+)-chimonanthine, (+)-folicanthine and (-)-calycanthine.