[Kikkert]

For a writing assignment I chose a synthesis that at some point uses a Curtius rearrangement. But it is strange.
The main point is that it leads to a decarboxylation.
It does not use an alcohol, and instead of introducing an amine group, it makes a C=C from a C-C. I cannot find a fitting reaction mechanism for this. It is said in the article that it is the minor product, but I'd still like to have a reaction mechanism for this. Literature is scarce.

This is the overall reaction, is it possible that DBU takes a proton from the carbon next to the O?

[pgk]

Question: Is any further working up procedure that involves water, e.g. purification by extraction or washing?