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enter image description here

Since $\ce{-CN}$ shows strong $\ce{-I}$ effect, there will be $\delta +ve$ charge on the carbon adjacent to it. Similarly, $\ce{-NO2}$ shows strong $\ce{-I}$ and $\ce{-M}$ effects.

So I this is my attempt: $\pi$ electrons are being donated to the electron deficient parts.

enter image description here

But the answer given in my book has $\ce{-CN}$ group at the third position to $\ce{-NO2}$ group.

Can someone please tell me where I have got my concepts wrong?

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  • $\begingroup$ Regardless of any simple electronic models, since DA part of what we call frontier orbital chemistry it should be dependend on orbital coefficients. There are tables for dienes and dienophiles and if I simply connect the sides with the biggest coefficients of the same symmetry I end up with your solution. Source: 10.1021/ja00793a069 $\endgroup$ – Justanotherchemist Nov 8 '18 at 9:52
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    $\begingroup$ It pains me to see that $\ce{-CN}$ group at an angle. $\endgroup$ – Martin - マーチン Nov 8 '18 at 13:57
  • $\begingroup$ @Martin what do you mean? $\endgroup$ – Archer Nov 8 '18 at 14:02
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    $\begingroup$ The first graphic, in $\ce{H2C=CH-C^{(1)}N}$, $\ce{C^{(1)}}$ is linearly coordinated not like it is depicted. It causes me mental pains. $\endgroup$ – Martin - マーチン Nov 8 '18 at 14:28
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    $\begingroup$ Not convinced by this DA reaction; both dienophile and diene are very electron-deficient... $\endgroup$ – orthocresol Dec 9 '18 at 11:12
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You pointed out correctly that $-CN$ has a great $-I$ effect but it won't bring a $+\delta$ on adjacent carbon atom, reason being it's instability. Apply electromeric effects on propanenitrile. Reaction

If you need help then just comment below :-)

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