Synthesis of alpha-(4-Oxazolyl)amino Esters via Bronsted Acid Catalyzed Tandem Reaction

Abstract

A one-step, Bronsted acid catalyzed tandem reaction for the synthesis of alpha-(4-oxazolyl)amino esters was developed. 4-Nitrobenzenesulfonic acid was found to be an efficient catalyst for the coupling of ethyl 2-oxobut-3-ynoates with amides to provide various a-(4-oxazolyl)amino esters. The experimental and X-ray crystallographic data suggest that a series of bond-forming reactions including imine formation, intermolecular Michael addition, and intramolecular Michael addition are functionalities.