Efficient approach for the parallel solid-phase synthesis of 1,1,3,4-tetrasubstituted-5-oxopiperazin-1-ium compounds

An efficient approach for the design and parallel solid-phase synthesis of unique tetrasubstituted oxopiperazinium derivatives is presented. The synthetic procedure involved a seven-step sequence carried out starting from resin-bound dipeptides. The desired compounds were obtained in good yields and high purity.