Reaction of chloroform with DBU

There's a certain reaction I've been doing that involves DBU (I've drawn the structure out below). The reaction is done in a flow machine (ie. high temperature and high pressure).
[![enter image description here](https://i.stack.imgur.com/JCYUh.png)](https://i.stack.imgur.com/JCYUh.png)
I've read that chloroform can't be used as a solvent for this reaction, because under the flow machine conditions DBU reacts with chloroform to form a side product.
I was interested in what this reaction is, so I've had a bit of a look but can't work it out. Here's what I'm thinking so far:


1. I've read that chloroform can react with base to form dichlorocarbene. There's no strong base here in this reaction, but could the high temperature/pressure conditions be causing this species to form? Dichlorocarbene could then react with DBU.
2. The only alternative I can think of is that chloroform does a nucleophilic substitution (with the DBU acting as electrophile)? Under normal conditions chloroform doesn't do nucleophilic substitution, but maybe under high temperature/pressure conditions it can. Also, DBU could potentially act as an electrophile in different ways:
[![enter image description here](https://i.stack.imgur.com/HdOl4.png)](https://i.stack.imgur.com/HdOl4.png)
Or alternatively, the enamine tautomer could potentially be the nucleophile:
[![enter image description here](https://i.stack.imgur.com/J4nc5.png)](https://i.stack.imgur.com/J4nc5.png)
Thanks for any help!




DBU is stronger base than you think. Strong enough to generate dichlorocarbene from chloroform under flow conditions as this reference shows [here](https://www.researchgate.net/profile/Qing-Wen-Song/publication/272131747_PEG400-enhanced_synthesis_of_gem-dichloroaziridines_and_gem-dichlorocyclopropanes_via_in_situ_generated_dichlorocarbene/links/5620947108aed8dd19404aa7/PEG400-enhanced-synthesis-of-gem-dichloroaziridines-and-gem-dichlorocyclopropanes-via-in-situ-generated-dichlorocarbene.pdf?origin=publication_detail).


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