3-Ylidenepiperazine-2,5-diones as versatile organic substrates

Abstract

3-Ylidenepiperazine-2,5-diones and 3,6-diylidenepiperazine-2,5-diones are cyclic dipeptides consisting of one or two didehydroamino acid moieties, respectively. Some compounds of this series occur in nature. They can easily be synthesised by several methods also in optically active form and are prone to addition reactions to the C–C double bond by electrophiles (enamine reactivity), nucleophiles (Michael reactivity), radicals, oxidising reagents or 1,3-dipoles, usually in a stereoselective manner. The resulting adducts can further be transformed to natural products and analogues or serve as precursors for interesting α-amino or α-keto acid derivatives by cleavage of the diketopiperazine ring.