Direct synthesis of β2,3‐amino acid from β‐hydroxycarbamides: Implication in the synthesis of azumamide analogs and conformational analysis

Abstract

AbstractThe designed β2,3 unnatural amino acids have been synthesized from α‐methyl‐β‐hydroxycarbamides via direct azidation without obtaining eliminated products. Furthermore, these β2,3 amino acids were utilized to synthesize cyclic tetrapeptides (CTPs) as azumamide analogs. 2D‐NMR analysis revealed the compact secondary structure as a single conformer. Presence of intramolecular H‐bonding in CTPs was observed in this α3β2,3 architecture and displayed a seven‐membered γ‐turn structure.