Finding reactant unsymmetrical diene that yields all four 1,2 and 1,4-addition products and the correct reaction pathways that lead to the 3 products

I completed 3/4 of the answers, by choosing the correct reaction pathways leading to each of the 3 different products. But I don't know how to draw the reactant diene, I really thought what I initially had was correct, should I make a trans reactant or is there something else missing?


1 Answer 1


Do we agree that the first step ist the addition of a proton to the diene? This is bit different from the addition of HCl to an alkene, where you would rely on the Markovnikov rule.

Here, stabilization of the cation through resonance comes into play.

I don't know how to draw it [...]

Draw stepwise!

positions to which a proton can add

In principle, a proton could add to one of the positions a to d.

How do the resulting cations look like and which of them are stabilized by resonance?

addition of proton to diene

Is it now a bit more clear?

  • $\begingroup$ I still don't quite understand, how should I alter my structure? $\endgroup$ Feb 9, 2014 at 7:10
  • $\begingroup$ @HarryJohnson Now it's me who doesn't understand ;) Do you mean the R as an abbreviation for the alkyl chain and that i didn't write out the terminal CH3? $\endgroup$ Feb 9, 2014 at 7:18
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    $\begingroup$ AH, I understand it now! Basically my initial answer was very close, but in order for it to go form the second product, both double bonds need to be shifted over one carbon toward the right. :) Thanks! $\endgroup$ Feb 9, 2014 at 7:27

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