Control of an Unusual Photo-Claisen Rearrangement in Coumarin Caged Tamoxifen through an Extended Spacer.
Control of an Unusual Photo-Claisen Rearrangement in Coumarin Caged Tamoxifen through an Extended Spacer.
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DOI：
10.1021/acschembio.6b00999
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发表时间：
2017-04-21
影响因子：
4
通讯作者：
Choi SK
中科院分区：
文献类型：
--
作者：
Wong PT;Roberts EW;Tang S;Mukherjee J;Cannon J;Nip AJ;Corbin K;Krummel MF;Choi SK
香豆素笼化分子的使用已经在许多光笼化应用中得到了很好的证明，包括对cre -雌激素受体（Cre-ERT2）重组酶活性的时空控制。在这篇文章中，我们报道了4-羟基他莫昔芬（4OHT）通过传统的醚键与香豆素笼化导致意想不到的光- claisen重排，这与游离4OHT的释放显著竞争。这种不希望发生的反应的基础似乎与香豆素结构及其基于自由基的脱壳机制有关，因为它没有发生在邻硝基苯（ONB）笼的4OHT中，否则以相同的方式连接。为了进行设计优化，我们引入了一种比醚连接更长的自焚连接体，并确定了一种最佳连接体，该连接体可以通过单光子和双光子吸收机制快速释放4OHT。在小鼠胚胎成纤维细胞（MEFs）中，研究了该构建体主动控制Cre-ERT2介导的基因修饰的能力，其中绿色荧光蛋白（GFP）报告依赖基因重组的表达由4OHT释放控制，并通过共聚焦荧光显微镜和流式细胞术检测。总之，我们报告了香豆素笼化化合物中这种光- claisen重排的意义，并展示了一种合理的连接策略来解决这种不想要的副反应。
The use of coumarin caged molecules has been well documented in numerous photocaging applications including for the spatiotemporal control of Cre-estrogen receptor (Cre-ERT2) recombinase activity. In this article, we report that 4-hydroxytamoxifen (4OHT) caged with coumarin via a conventional ether linkage led to an unexpected photo-Claisen rearrangement which significantly competed with the release of free 4OHT. The basis for this unwanted reaction appears to be related to the coumarin structure and its radical-based mechanism of uncaging, as it did not occur in ortho-nitrobenzyl (ONB) caged 4OHT that was otherwise linked in the same manner. In an effort to perform design optimization, we introduced a self-immolative linker longer than the ether linkage and identified an optimal linker which allowed rapid 4OHT release by both single-photon and two-photon absorption mechanisms. The ability of this construct to actively control Cre-ERT2 mediated gene modifications was investigated in mouse embryonic fibroblasts (MEFs) in which the expression of a green fluorescent protein (GFP) reporter dependent gene recombination was controlled by 4OHT release and measured by confocal fluorescence microscopy and flow cytometry. In summary, we report the implications of this photo-Claisen rearrangement in coumarin caged compounds and demonstrate a rational linker strategy for addressing this unwanted side reaction.