# Regioselectivity for electrophilic aromatic substitution with multiple strongly electron withdrawing groups

At which position will electrophilic substitution on p-cyanonitrobenzene occur?

As both are -M groups, there are two possible sites of reaction, meta to each of the groups.
The answer is meta to $\ce{CN-}$. Why is this so? According to me it should be meta to $\ce{NO2}$, because $\ce{NO2}$ is the stronger -M group?

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• For such compound most eletrophilic subst. wouldn't work – Mithoron Aug 27 '15 at 12:15