Carboxyl-protecting groups convertible into activating groups. Carbamates of o-aminoanilides are precursors of reactive N-acylureas

Abstract Selected carbamates of o -aminoanilides of amino acid derivatives are stable under neutral and acidic aqueous conditions but undergo a quantitative base-catalysed intramolecular conversion into an 1-acylbenzimidazolin-2-one. The pH-rate profiles for this reaction and for the subsequent hydrolysis of the N -acylurea were established. The N -acylurea displays a hydrolytic reactivity reaching that of active esters and is shown to acylate leucine methyl ester.