original stereocontrolled transannular rearrangement starting from activated 2,5-diketopiperazines has been developed, an opportunity for the medicinal chemistry field, which requests access to novel biological scaffolds. This powerful ring contraction, which can be related to a stereoselective aza-version of the Chan rearrangement, allows for example the one-step synthesis of various tetramic acids, access
A facile and efficient synthesis of novel seven-membered heterocyclic derivatives containing 3-aminoazepan-2-one backbone is described using 1,4-protected piperazine-2,5-diones and alkynes as starting materials. The reaction may undergo Michael addition, unusual nucleophilic attack to an amide group, and keto-enol tautomerization. The reaction showed different reactivity when using substrates with different protecting groups: it had higher efficiency when using either alkanoyl-protecting group with cesium carbonate as the base, or benzoyl-protecting group with triethylamine as the base, but no reaction when using benzyl or allyl protecting groups with a variety of bases (Et3N, DBU, K2CO3, Cs2CO3, KHCO3, CsHCO3, and KOt-Bu).