Breaking the bottleneck: stilbene as a model compound for optimizing 6π e- photocyclization efficiency

TEMPO was more suitable at photocyclizing stilbene than iodine. As stilbene concentration increased, TEMPO produced a higher yield of phenanthrene at shorter times and significantly reduced the potential for undesired [2+2] cycloadditions. Iodine retarded phenanthrene formation because it promoted isomerization to (E)-stilbene which encouraged [2+2] cycloaddition.

Automated summary

TEMPO was found to be more suitable for the photocyclization of stilbene compared to iodine, resulting in higher yields of phenanthrene in shorter times and reduced undesired [2+2] cycloadditions. Iodine was shown to retard phenanthrene formation by promoting isomerization to (E)-stilbene, which in turn encouraged [2+2] cycloaddition reactions.