I was given the following reaction to prove a mechanism for:

enter image description here

and I managed to prove the first step with ease. enter image description here

The second step, forming the "base-catalysed aldol" is the part that's rather confusing me.

Consider the mechanism of a base-catalysed aldol reaction below.

enter image description here

For this reaction to take place, I need a second carbonyl molecule, but the $\ce{CO2Me}$ on the right hand side ring appears untouched, and likewise so does the carbonyl group on the left hand side too.

I tried the reaction a second way (giving the mechanism below) but am unsure if this is correct.
Is this the correct mechanism?

enter image description here

enter image description here

  • 1
    $\begingroup$ Looks mostly reasonable to me. There’s an alkene missing from your final product though. Also, in the final elimination you’ve drawn an E2 reaction, but OH typically isn’t a good enough leaving group to do this. Can you think of an alternative elimination pathway? $\endgroup$ – PCK Jun 12 at 21:04

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