Rearrangement of a Di-t-butyl Aryl Phosphate to a Di-t-butyl (2-Hydroxyaryl) phosphonate. A Convenient Preparation of (2-Hydroxyphenyl)-and (2-Hydroxy 5-Methoxy Phenyl) Phosphonic Acids

Abstract

(2-Hydroxyphenyl) phosphonic acid 4a phosphorus analogue of salicylic acid is to date a difficultly accessible compound. The two reported preparations of 4a start with difficultly available starting materials and give poor overall yields. Whereas Freedman1 obtained 4a in 16% overall yield starting with (2-nitro phenyl) benzyl ether and reported a melting point of 124–127°C, Lukin and Kalanina² claimed to have obtained 4a in 41% yield by the treatment of (2-brornophenyl) phosphonic acid with aq. ammonia in presence of cuprous oxide³ and reported a melting point of 178–179°C. In addition to the difference in melting point, the products obtained by the above two methods seemed to differ in their solubility in water.