An Access to Aza-Freidinger Lactams and <i>E</i>‑Locked Analogs

Freidinger lactams, possessing a peptide bond configuration locked to <i>Z</i>, are important key elements of conformationally restricted peptidomimetics. In the present work, the C_αH_<i>i+</i>1 unit has been replaced by N, leading to novel aza-Freidinger lactams. A synthesis to corresponding building blocks and their <i>E</i>-locked analogs is introduced. The versatile buildings blocks reported here are expected to serve as useful elements in peptide synthesis

Synthesis of 1‑Arylcycloalkenamines by Intramolecular Arylation of Lithiated Ureas

The deprotonation of <i>N</i>′-arylurea derivatives of cyclohexenamines by alkyllithiums leads to migration of the <i>N</i>′-aryl substituent from N′ to the allylic position α to N via rearrangement of a urea-stabilised allyllithium intermediate. The product ureas may be solvolysed to reveal 1-arylcyclohexenamines