Fries Rearrangement of 2-Biphenylyl Benzoate and 2-Biphenylyl Acetate

Abstract

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 phenyl ketone(5) were obtained as the rearrangement products, with a small amount of 2-biphenylol. Rearrangement products 2-hydroxy-3-biphenylyl methyl ketone(6), 2-hydroxy-5-biphenylyl methyl ketone(7), and 2'-hydroxy-4-biphenylyl methyl ketone(8) were obtained in the reaction of 2-biphenylyl acetate(2) with AlCl₃ under the same reaction conditions. The yield of para-rearranged product 4 decreased with increases of the reaction time because of taking place reverse Fries rearrangement, isomerization and deacylation of 4. The yield of 7 also decreased because of reverse Fries rearrangement to 2.
The yield of para-rearrangement product 4 decreased with increasing amounts of AlCl₃. Although the Fries rearrangement of biphenylyl esters 1 and 2 may proceed via both an inter- and intramolecular pathways, the benzoate 1 showed a higher probability of intermolecularity in compared to the acetate 2.