Help with mechanism: Isomerization of eugenol

I'm confused about the mechanism for the isomerization of the external alkene eugenol to the internal alkene isoeugenol. I've added an image below of their structures.


[![enter image description here](https://i.stack.imgur.com/WkCBo.png)](https://i.stack.imgur.com/WkCBo.png)


The reaction is usually carried out using a strong base (sodium or potassium hydroxide) in a polyol solvent (typically glycerol or ethylene glycol).


I have no idea why this might happen, especially given that there's no carbonyls with acidic alpha carbons in the molecule. Maybe eugenol phenoxide is responsible?


