Regio-and stereoselective aziridine ring opening with oxygen nucleophiles derived from serine and threonine provides a route to stereochemically pure 4-oxa-2, 6-diaminopimelic acid (oxa-DAP) and its methyl-substituted derivatives. Oxa-DAP is a substrate of DAP epimerase, a key enzyme for biosynthesis of l-lysine and formation of peptidoglycan precursors. Orthogonally protected analogues of lanthionine and β-methyllanthionine ...