Synthesis of a conformationally restricted substrate analogue of siderophore biosynthetases.

A conformationally restricted analogue (5) of Nω-acetyl-Nω-hydroxyornithine and -lysine was synthesized. The synthesis features an efficient acylnitroso hetero-Diels−Alder cycloadduct (1) ring opening with palladium(0) and methylnitroacetate.