Synthetic Approach to the Natural -Nitrosohydroxylamino Tetramic Acid JBIR-141.

An analogue of the metabolite JBIR-141, featuring a delicate -nitrosohydroxylamine, a 3-acyltetramic acid, and an oxazoline, was synthesized by a convergent strategy from l-alanine, l-threonine, and l-glutamic acid. Key steps were the cyclization of an Ala-Thr derivative to give the oxazoline, a Dieckmann condensation affording the 3-acyltetramic acid, and the -nitrosation of a hydroxylamino derivative of glutamic acid. An adequate protecting group strategy was established for coupling the three building blocks.