Aromatics acylation methyl benzoate

Hwang, J. P., Prakash, G. K. S., and Olah, G. A. 2000. Trifluoromethanesulfonic acid catalyzed novel Friedel-Crafts acylation of aromatics with methyl benzoate. Tetrahedron 56 7199-7203. 

Triflic acid-catalyzed Friedel-Crafts acylation reactions of aromatics with methyl benzoate give benzophenone products in good to excellent yields (eq 33). To explain the high level of electrophilic reactivity of this system, protosolvated species are proposed as possible intermediates (eq 32). In the triflic acid-catalyzed cyclization of some ethylene dications, protonation of the ester group is thought to be a key activation step. Reaction of a-(methoxycarbonyl)diphenylmethanol with TfOH gives the fluorene product in 94% yield (eq 34). ... 

Acylations. Catalyzed by graphite the Friedel-Crafts acylation as well as the transformation of ethers to esters by acyl halides in refluxing 1,2-dichloroethane are realized. Although aliphatic chlorides are inferior to aromatic halides this method is quite general as shown by the synthesis of benzoates (e.g., allyl benzoate from allyl benzyl ether and methyl benzoates from methyl f-butyl ether). 

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