Contra‐Thermodynamic,Photocatalytic E→Z Isomerization of Styrenyl Boron Species: Vectors to Facilitate Exploration of Two‐Dimensional Chemical Space |
| |
| Authors: | M?Chem John J Molloy Dr Jan B Metternich Dr Constantin G Daniliuc Dr Allan J B Watson Prof?Dr Ryan Gilmour |
| |
| Institution: | 1. WESTCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, UK;2. http://www.uni‐muenster.de/Chemie.oc/gilmour/;3. Organisch Chemisches Institut, Westf?lische Wilhelms-Universit?t Münster, Münster, Germany;4. Current address: Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA;5. EASTCHEM School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, UK |
| |
| Abstract: | 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 of readily accessible E‐α‐substituted styrenyl BPins to generate the corresponding Z‐isomers with high fidelity. Preliminary validation of this contra‐thermodynamic E→Z isomerization is demonstrated in a series of stereoretentive transformations to generate Z‐configured trisubstituted alkenes, as well as in a concise synthesis of the anti‐tumor agent Combretastatin A4. |
| |
| Keywords: | alkenes boron conformational analysis isomerizations natural products |
|
|
