In my textbook, Strategic Applications of Named Reactions in Organic Synthesis, the author says the following regarding properties of the Meerwein arylation:
The general features of this reaction are:
1) the procedure is simple; no special laboratory equipment is needed;
2) the aryldiazonium halides are prepared by the diazotization of aromatic amines using sodium nitrite and aqueous hydrohalic acids and are not isolated, rather immediately reacted with the alkenes in the presence of an organic solvent (e.g., acetone, acetonitrile);
3) the presence of electron-withdrawing substituents on the aromatic ring tends to increase the yield, whereas electron-donating groups often give lower yields;
4) the alkene component usually has an electron-withdrawing substituent and mostly α,βunsaturated carbonyl compounds are used;
I don't really understand why that is. If anything, I would think that EDG's (in para position) would increase the yield because they stabilize the aryl cation that would form if the aryl diazonium decomposes and loses its diazo group as nitrogen gas (N2).
Could it be that an EDG would make the aryl diazonium compound too unstable and decompose too quickly? Allowing for side reactions to occur?