Total synthesis of exochelin MN and analogues.

The first total synthesis of exochelin MN is described along with rationally designed analogues. The required L-threo-beta-hydroxyamino acid components were constructed using either Sharpless asymmetric aminohydroxylation reactions or an aldol reaction of imidazolidinone 19. A new concise procedure for the preparation of the constituent six-membered cyclic hydroxamate was developed. In addition, a plausible mechanism for exochelin MN-mediated iron(III) transport was proposed. Biological studies of these compounds will be used to evaluate this hypothesis.