Conformationally defined piperazine bis(N-oxides) bearing amino acid derived side chains

Abstract

The preparation of a number of piperazine derivatives bearing amino acid substituents on the nitrogen is described; these compounds undergo oxidation with MCPBA to yield bis(N-oxides) in which both oxygen atoms are axially orientated and hydrogen bonded to the amide NHs, giving highly defined conformations to the molecules; the structure of the valine derivative (8c) was confirmed by X-ray analysis.