OxymaPure (ethyl 2-cyano-2-(hydroxyimino)acetate) was tested as an
additive for use in the carbodiimide (DIC) approach for the synthesis of a novel series of
α-ketoamide derivatives (4-[2-(2-acetylaminophenyl)-2-oxo-acetylamino]benzoyl amino
acid ester derivatives). OxymaPure showed clear superiority to HOBt/DIC or carbodiimide
alone in terms of purity and yield. The title compounds were synthesized via the ring
opening of N-acylisatin. First, N-acetylisatin was reacted with 4-aminobenzoic acid under