Contra-Thermodynamic, Photocatalytic <i>E</i>
→<i>Z</i>
Isomerization of Styrenyl Boron Species: Vectors to Facilitate Exploration of Two-Dimensional Chemical Space
作者:John J. Molloy、Jan B. Metternich、Constantin G. Daniliuc、Allan J. B. Watson、Ryan Gilmour
DOI:10.1002/anie.201800286
日期:2018.3.12
Designing strategies to access stereodefined olefinic organoboron species is an important synthetic challenge. Despite significant advances, there is a striking paucity of routes to Z‐α‐substituted styrenyl organoborons. Herein, this strategic imbalance is redressed by exploiting the polarity of the C(sp2)−B bond to activate the neighboring π system, thus enabling a mild, traceless photocatalytic isomerization
获得立体定义的烯烃有机硼物种的设计策略是一项重要的合成挑战。尽管取得了重大进展,但到Z -α-取代的苯乙烯基有机硼的途径却很少。在本文中,通过利用C(sp 2)-B键的极性激活相邻的π系统来解决这一战略性不平衡问题,从而使易于获得的E -α-取代的苯乙烯基BPins发生温和,无痕的光催化异构化,从而生成相应的高保真Z异构体。一系列立体保持性转化生成Z证明了这种对热力学E → Z异构化的初步验证配置的三取代烯烃,以及抗肿瘤药物Combretastatin A4的简明合成。