One-step diketopiperazine synthesis using phase transfer catalysis

A simple and efficient one-step procedure is described for the synthesis of a number of symmetrical 1,4-disubstituted piperazine-2,5-diones under phase transfer conditions. The reactions are carried out at room temperature, starting from a suitable N-chloroacetamide in the presence of an aqueous solution of sodium hydroxide. Piperazine-2,5-diones were obtained with excellent selectivity in yields of up to 90%.