An unusual rearrangement involving the conversion of an O-aryl ether (1) into ortho- (2) and para- (3) hydroxy aryl systems, dependant upon conditions, was discovered during our studies towards the total synthesis of diazonamide A.

Upon treatment of 1 under thermal conditions (benzene, 80 °C, sealed tube) clean rearrangement to the ortho-hydroxy isomer 2 was observed. Under acid catalyzed conditions the para-hydroxy isomers 3 were predominant (Scheme 1). The rearrangement was also responsive to Lewis acid catalysis: exposure of 1 to Cu(OTf)₂, AgOTf and TiCl₄ gave 3.The rearrangement was tolerant to a variety of R groups in the 3-position (Ph, Et, allyl, i-Pr) and to an array of 2- and 4- substituents on the aromatic ring (R¹/R² : Me, Cl, OMe, NO₂). Subjecting 1 and equimolar 4-i-PrC₆H₄OH to the rearrangement conditions resulted in a 1:1 mixture of products; establishing that the rearrangement exhibited crossover. This is classical evidence for a dissociative S_N1 mechanism. In order to increase the scope and utility of the reaction, the effects of replacing the ether linkage of 1 with an amine or a thio linkage are being investigated. Consideration is also being given to the application of the rearrarangement to the total synthesis of natural products.