TBR "Worst Dienophile" Question

[justadream]

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TBR Ochem page 300 (book 1) #54

I understand that bad dienophiles have electron-donating groups attached to them. However, one of the structures is an alkyne with the two substiuents on each end being "COCH2CH3"

TBR says these groups are "esters". How is that an ester? I only see one oxygen.

I originally treated them like electron-donating groups (similar to like "OCH3") but apparently it's an ester?

 

[lNVlNClBLE]

Uh. I don't think Diels-Alder reactions are required knowledge for the MCAT.

Also, if it says ester with one oxygen, I'm assuming it's an error. 😛

 

[lumpyduster]

Looks more like a ketone to me. That first carbon would have 2 hydrogens if it was an ether group. So if it's a ketone it's still electron withdrawing at least 🙂