Boron-enabled geometric isomerization of alkenes via selective energy-transfer catalysis
Boron-enabled geometric isomerization of alkenes via selective energy-transfer catalysis
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DOI：
10.1126/science.abb7235
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发表时间：
2020-07-17
期刊：
影响因子：
56.9
通讯作者：
Gilmour, Ryan
中科院分区：
文献类型：
--
作者：
Molloy, John J.;Schaefer, Michael;Gilmour, Ryan
基于异构化的策略使得能够从几何定义的烯烃连接针中以立体发散的方式构建复杂的多烯仍然明显不发达。在理想的低分子质量前体中考虑原子效率，进一步阻碍了缓解异构化所固有的热力学限制。在这项工作中，我们报道了一种通用的双亲C-3支架，它可以异构化和双向延伸。基于高效的三重态能量转移，β-乙基丙烯酸酯的选择性异构化依赖于底物生色团中的硼p轨道的参与。C(sp(2))-B键在产物中旋转90度会导致重新激发效率低下，并赋予方向性。这种微妙的立体电子门控机制使得立体控制合成定义明确的维甲酸衍生物成为可能。
Isomerization-based strategies to enable the stereodivergent construction of complex polyenes from geometrically defined alkene linchpins remain conspicuously underdeveloped. Mitigating the thermodynamic constraints inherent to isomerization is further frustrated by the considerations of atom efficiency in idealized low-molecular weight precursors. In this work, we report a general ambiphilic C-3 scaffold that can be isomerized and bidirectionally extended. Predicated on highly efficient triplet energy transfer, the selective isomerization of beta-borylacrylates is contingent on the participation of the boron p orbital in the substrate chromophore. Rotation of the C(sp(2))-B bond by 90 degrees in the product renders re-excitation inefficient and endows directionality. This subtle stereoelectronic gating mechanism enables the stereocontrolled syntheses of well-defined retinoic acid derivatives.