通过中性氨基自由基的串联环化快速获得花萼 A 和 Daphnicyclidin A 型 Daphniphyllum 生物碱的杂环核心
摘要:
介绍了一种对花萼 A 和 daphnicyclidin A 型Daphniphyllum生物碱的含叔胺核心的简化方法。一种已知的香芹酮衍生物只需四次合成操作即可转化为核心结构,并且已经做好了进一步阐述的准备。关键的实现方法是自由基环化级联反应,首先在烯酮的 β 位添加二级中性氨基自由基,然后用悬垂的炔烃捕获。
通过中性氨基自由基的串联环化快速获得花萼 A 和 Daphnicyclidin A 型 Daphniphyllum 生物碱的杂环核心
摘要:
介绍了一种对花萼 A 和 daphnicyclidin A 型Daphniphyllum生物碱的含叔胺核心的简化方法。一种已知的香芹酮衍生物只需四次合成操作即可转化为核心结构,并且已经做好了进一步阐述的准备。关键的实现方法是自由基环化级联反应,首先在烯酮的 β 位添加二级中性氨基自由基,然后用悬垂的炔烃捕获。
Tin-Free Access to the ABC Core of the Calyciphylline A Alkaloids and Unexpected Formation of a D-Ring-Contracted Tetracyclic Core
作者:Alberto M. Lopez、Ahmad A. Ibrahim、Gregory J. Rosenhauer、Hansamali S. Sirinimal、Jennifer L. Stockdill
DOI:10.1021/acs.orglett.8b00544
日期:2018.4.20
strategy for the successful cyclization of a variety of internal alkyne-containing N-chloroamine precursors to the ABC core viacyclization of a neutral aminyl radical is established. Deuterium labeling experiments confirm that the solvent is the primary source of the final H atom in the cyclization cascade. These conditions enabled a streamlined route to a β-ketoester intermediate poised for intramolecular
建立了一种无锡策略,通过中性氨基自由基的环化,成功地将各种含炔的N-氯胺前体环化至 ABC 核心。氘标记实验证实溶剂是环化级联中最终氢原子的主要来源。这些条件为制备 β-酮酯中间体提供了一条简化的路线,该中间体准备进行分子内 Knoevenagel 缩合,以构建 calcciphylline A 生物碱的七元 D 环。然而,在高温下暴露于t -BuOH 中的 CsF 会导致意想不到的脱羧反应,形成 D 环收缩的四环核。
Toward the ABCD core of the calyciphylline A-type Daphniphyllum alkaloids: solvent non-innocence in neutral aminyl radical cyclizations
作者:Jennifer L. Stockdill、Alberto M. Lopez、Ahmad A. Ibrahim
DOI:10.1016/j.tetlet.2015.01.121
日期:2015.6
The Daphniphyllum alkaloids remain an attractive target in the synthetic community because of their unique framework and promising biological activities. We have shown that the ABC core of the calyciphyllineA-typealkaloids can be rapidly accessed via the tandem cyclization of a neutral aminyl radical with a polarized cyclic olefin. Deuterium labeling experiments and reactions omitting a tin hydride
Rapid Access to the Heterocyclic Core of the Calyciphylline A and Daphnicyclidin A-Type <i>Daphniphyllum</i> Alkaloids via Tandem Cyclization of a Neutral Aminyl Radical
作者:Ahmad A. Ibrahim、Alexander N. Golonka、Alberto M. Lopez、Jennifer L. Stockdill
DOI:10.1021/ol4034868
日期:2014.2.21
A streamlined approach to the tertiary amine-containing core of the calyciphylline A and daphnicyclidin A-type Daphniphyllum alkaloids is presented. A known carvone derivative is converted into the core structure in only four synthetic operations, and it is well poised for further elaboration. The key enabling methodology is a radical cyclization cascade beginning with addition of a secondary, neutral
介绍了一种对花萼 A 和 daphnicyclidin A 型Daphniphyllum生物碱的含叔胺核心的简化方法。一种已知的香芹酮衍生物只需四次合成操作即可转化为核心结构,并且已经做好了进一步阐述的准备。关键的实现方法是自由基环化级联反应,首先在烯酮的 β 位添加二级中性氨基自由基,然后用悬垂的炔烃捕获。