Design and Synthesis of Diversely Substituted Azacyclic Inhibitors of Endothelin Converting Enzyme

A series of azacyclic phosphonic acids were synthesized from l-pyroglutamic acid, 6-oxo-l-pipecolic
acid, and their enantiomers. The objective was to study the effect of constraining acyclic inhibitors of
endothelin converting enzyme on inhibitory activity. Potential pharmacophoric tethers were introduced
by stereocontrolled reactions to give highly substituted pyrrolidine- and piperidine-α-phosphonic acids.
Weak inhibitory activity was observed for one diastereomer in each series having the same relative
orientation of substituents.