An unprecedented rearrangement of salicylanilide derivatives: imidazolinone intermediate formation

The preparation of new prodrug forms of anti-tuberculosis active salicylanilide esters with amino acids led to an unexpected rearrangement. The isolation and the structure determination of 2-(5-chloro-2-hydroxyphenyl)-3-(3-chlorophenyl)-5-substituted-3,5-dihydro-4H-imidazol-4-ones unambiguously confirm one of the two proposed reaction mechanisms.