Synthesis of ( <i>Z</i> )-Stilbene through the Combination of Olefin Metathesis and Photoisomerization

This work presents a novel organic chemistry experiment for the synthesis of (Z)-stilbene through a combination of olefin metathesis and photoisomerization. The experiment is designed to help students grasp the mechanisms and master practical execution of these transformations and to train them with the laboratory skills involved in the execution of the experiment while also teaching them to determine the Z/E ratio of stilbene using NMR spectroscopy. A distinctive feature of this experiment is its integration of olefin metathesis and photoisomerization in an undergraduate laboratory setting. Typically, classical olefin metathesis reactions yield the E configuration as the major product. In this tandem experiment, however, the Z configuration is obtained via in situ photoisomerization of the E isomer produced through olefin metathesis. This allows students to deepen their understanding of how photocatalysis influences olefin stereochemistry, reinforcing both their theoretical knowledge and their experimental observations. The experimental procedure is completed within 4 h, yielding (Z)-stilbene in 74% yield with a Z:E ratio of 8:1.