[Research on nitrogen heterocyclic compounds. IX. Synthesis of 5-hydroxy-2,4-dicarbethoxypyrroles]

Reaction between diethyl ethoxymethylenemalonate and N-substituted diethylaminomalonates in the presence of sodium ethoxide gives 5-hydroxy-2,4-dicarbethoxypyrroles. By treating these compounds with acetic anhydride we shall get the corresponding 5-acethoxy-2,4-dicarbethoxypyrroles and, by catalytic reduction, the corresponding 2,4-dicarbethoxy-5-pyrrolidinones, which in turn are hydrolyzed to the well known corresponding pyroglutamic acids. The I.R. and N.M.R. spectral data are in agreement with the proposed structures.