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 C₃ scaffold that can be isomerized and bidirectionally extended. Predicated on highly efficient triplet energy transfer, the selective isomerization of β-borylacrylates is contingent on the participation of the boron p orbital in the substrate chromophore. Rotation of the C(sp²)–B bond by 90° 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.

基于异构化的策略，能够使由几何定义的烯烃关键构形的复杂多烯立体发散地构建仍然明显欠发达。理想化的低分子量前体中对原子效率的考虑，进一步减轻了异构化固有的热力学约束。在这项工作中，我们报告了一个通用的C ₃支架，该支架可以异构化并双向延伸。基于高效的三重态能量转移，β-硼丙烯酸酯的选择性异构化取决于硼p轨道在底物发色团中的参与。C（sp ^2的旋转）–产品中90°的B键使重新励磁效率低下并赋予方向性。这种微妙的立体电子门控机制可实现清晰定义的视黄酸衍生物的立体控制合成。