Transformation of acyl group to carboxyl group in biphenyl system with two acyl groups at para position

How do I perform this reaction?


I have prepared 4,4'-acylbiphenyl and want to make one acyl group into $\ce{-OH}$ and other into $\ce{-COOH}$ group. 




Is it correct that you are aiming to synthesize 4-(4-hydroxyphenyl)benzoic acid [58574-03-1]?


![4-(4-hydroxyphenyl)benzoic acid](https://i.stack.imgur.com/EgiFL.png)


The target compound is available in one step from biphenyl using potassium peroxydisulfate $(\ce{K2S2O8})$ as an oxidant, Palladium(II)-trifluoroacetate, $\ce{Pd(OCOCF3)2}$, as a catalyst, and formic acid as the carbon source for the $\ce{-COOH}$ group. The synthesis was published in  

*Org. Lett.*, **2004**, *6*, 2437-2439 ([DOI](http://dx.doi.org/10.1021/ol049166l)).




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**EDIT**


Limited resources and experience will probably rule out *Stille*-type coupling reactions too. 


Alternatives pretty much depend on which 4,4'-disubstituted biphenyl are available.


A methoxyarene can be converted to the corresponding phenol by $\ce{BBr3}$  

or the cheaper hydrobromic acid. The $\ce{-OCH3}$ group resists oxidation, is a **+M** substituent and is not acidic. All this might be helpful (see below).


In order to introduce the $\ce{-COOH}$ substituent, two approaches seem to be possible in an undergrade lab:


* oxidation of a methyl group by permanganate
* *Grignard* reaction of a bromoarene with carbon dioxide


![retrosynthesis](https://i.stack.imgur.com/3st78.png)


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