[greentea11]

Can't see how to get to product?
Question says suggest a synthesis, using any reagent, could be multiple steps

reaction is attached

So I thought you could maybe enolise the carbonyl, have it attack a halogen ester to get the, but then youre left with the butyl ring

How does the butyl ring react?

help appreciated

[stanleyykk]

1. Use 1.DIBAL, -78oC 2. H2O, Result in acetaldehyde + cyclobutanol
2. Take acetaldehyde and add ethyl 1-Bromo-ethanoate
3. I don't remember if you need an acidic workup (I just came back from exam and I already forgot everything.... Sorry about that.)

I think the reaction you are looking for is called Clasien Condensation 

[discodermolide]

Perhaps you could start off with a Bayer-Villiger reaction and see where you can go from there.

[orgopete]

I presume that is a retrosynthesis arrow. If so, just refresh acetoacetate chemistry.

[zsinger]

Where do you see a halogen?  I would heed disco's advice .
             -Zack

[orgopete]

Where do you see a halogen?  I would heed disco's advice .
             -Zack

Huh? If this is a student question, I can see how acetoacetate could be very easily into the cyclobutane. I think this would be a very difficult problem to make ethyl acetoacetate from acetylcyclobutane. I still think this looks like the kind of problem that is appropriate for a retrosynthesis.

[zsinger]

He mentioned a halogen in his question.  I just didn't see one in any of the steps…..(For instance, an arrow with "-HBr" likely indicating a substitution reaction has occurred.  Must be a retro-synth, your right.
          -Zack
                   

[greentea11]

Sorry for the confusion.
I agree it should be a resynthesis arrow, which makes the problem straight forward

Thanks for pointing it out