Fries rearrangement of 2-biphenylyl benzoate and 2-biphenylyl acetate

When 2-biphenylyl benzoate(1) was treated with anhydrous aluminum chloride( AlCl3) in boiling o-dichlorobenzene, 2-hydroxy-3-biphenylyl phenyl ketone(3 ), 2-hydroxy-5-biphenylyl phenyl ketone (4), and 2'-hydroxy-4-biphenylyl ph enyl ketone(5) were obtained as the rearrangement products, with a small am ount of 2-biphenylol. Rearrangement products 2-hydroxy-3-biphenylyl methyl ketone(6), 2-hydroxy-5-biphenylyl methyl ketone(7), and 2'-hydroxy-4-biphen ylyl methyl ketone(8) were obtained in the reaction of 2-biphenylyl acetate (a) with AlCl3 under the same reaction conditions. The yield of para-rearra nged product 4 decreased with increases of the reaction time because of tak ing place reverse Fries rearrangement, isomerization and deacylation of 4. The yield of 7 also decreased because of reverse Fries rearrangement to 2. [GRAPHICS] The yield of para-rearrangement product 4 decreased with increasing amounts of AlCl3. Although the Fries rearrangement of biphenylyl esters 1 and 2 ma y proceed via both an inter- and intramolecular pathways, the benzoate 1 sh owed a higher probability of intermolecularity in compared to the acetate 2 .