Peptides Incorporating 3,4-Dihydroxyprolines: Synthesis and Structural Study

Conversion of Hydroxyproline “Doubly Customizable Units” to Hexahydropyrimidines: Access to Conformationally Constrained Peptides

“…With respect to the formation of peptide turns ( IV ), our in situ-formed nitrogen heterocycles would serve as “turn templates”. The literature reports other natural and synthetic turn templates (such as morpholino-, piperazine-, indolizidine-, bicyclic lactam-, and dibenzofuran-containing amino acids, among others), − but unlike them, the hexahydropyrimidines would be formed during peptide ligation, allowing in situ turn generation at specific positions. Since the starting aldehydes 5 can have S or R chains, the conformation of the molecule can be modulated.…”