Piperazic acids (R)- and (S)-1, cyclic α-hydrazino acids, are not only components of several naturally occurring cyclodepsipeptides [1] and [2] with remarkable biological activities, but also useful synthetic intermediates in the preparation of medicinally important compounds, such as enzyme inhibitors. 3 To construct polyoxypeptins and GE3, 4 cyclodepsipeptides containing piperazic acids, in the quantities required for biological evaluation, we needed to produce ...
