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In class, we learned that Diels-Alder reactions only occurs with s-cis conformations and that conformations like those in cyclopentadiene are permanently locked in a cis-transformation and that is why they are so reaction. We also learned that the reaction proceeds at a higher rate with an electro-withdrawing substituent (eg. carbonyl) . Why then is a molecule like the one in the figure not reactive while a similar structure, a cyclopentadienone, is?enter image description here

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  • $\begingroup$ Whoa, carbonyl isn't a substituent here, but part of ring, which isn't a flat one... Also why do you even think it is or isn't reactive? $\endgroup$ – Mithoron Jan 30 '18 at 20:58
  • $\begingroup$ Compared to cyclopentadienone? Well, since both molecules have s-cis bonds, thats probably not it. Also, according to my textbook, carbonyl groups increase rxn rate because they are electron withdrawing due to resonance and both structures have resonance structures. Perhaps because cyclopentadienone has more ring strain? Im not really sure though cause I can't picture the structure of the molecule in the figure. $\endgroup$ – Sarah Smith Jan 30 '18 at 21:07
  • $\begingroup$ Actually, why would have a electron withdrawing carbonyl group and the fact that they produce resonance structures increase the rate of reaction? $\endgroup$ – Sarah Smith Jan 30 '18 at 21:15
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    $\begingroup$ Cycloundecapentaenon is so different and incomparable that I have no idea why you picked this compound. $\endgroup$ – Mithoron Jan 30 '18 at 21:26
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You need to draw this structure in a 3D visualizer program, eg, Avogadro. While this structure looks similar to cyclopentadiene, in 3D it looks vastly different. enter image description here

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    $\begingroup$ Is that the all-cis isomer? One of the double bonds at the back looks like it’s trans to me. $\endgroup$ – orthocresol Jan 30 '18 at 21:08
  • $\begingroup$ You are correct. The all cis conformation does have the similar problem as well. $\endgroup$ – SamL Jan 30 '18 at 21:44
  • $\begingroup$ You should probably edit the image. (Btw, it’s configuration not conformation.) $\endgroup$ – orthocresol Jan 31 '18 at 9:34

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