Ortho-regioselective Fries rearrangement

Since the Fries rearrangement is a equilibrium reaction, the reverse reaction may be used preparatively under appropriate experimental conditions. An instructive example, which shows how the regioselectivity depends on the reaction temperature, is the rearrangement of m-cresyl acetate 8. At high temperatures the ortho-product 9 is formed, while below 100°C the para-derivative 10 is formed ... 

The amide is a good ort/zo-director but so is the acetal function. The regioselectivity (actually there is the issue of chemoselectivity here too) of the lithiation reaction will depend upon which of the two is the more potent. Amides were one of our three kings of the ortho-directors and are more powerful than acetals. Now it is time for an anionic Fries rearrangement (in the retrosynthetic direction) to give the starting material 127. 

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