Birch reduction substituent effects

Substituent effects are in accord with the proposed mechanism. The Birch rule202 states that electron-releasing substituents (alkyl groups) deactivate the ring and direct reduction so that the major product has the maximum number of groups attached to the residual double bonds, that is, to vinyl positions. In other words,... 

The effect of electron-withdrawing substituents on the Birch Reduction varies. For example, the reaction of benzoic acid leads to... 

The synthon resulting from disconnections A and C was first synthesised (refs. 282, 283) as an aryidienal compound (P) commencing with gallic acid by Birch reduction, transformation of the ethoxy I group to a basic substituent and the ethoxycarbonyl to a dienal structure in the following way (route a). The attachment of the C4 chain to the benzyl iodide at step ix was effected with the intermediate obtained by (route b). 

The Birch reduction also involves electron transfer to aromatic rings. In order to understand the substituent effect on the sites of reduction, it is instructive to consider the relative stabilities of the following structures ... 

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