title: Synthesis of hexa- and pentasubstituted diketopiperazines from sterically hindered amino acids.
abstract: Steric hindrance assists in the formation of hindered diketopiperazines using acyl-transfer coupling. In acyl-transfer coupling, the carboxylate of an unprotected N-alkylamino acid attacks an active ester to form a transient anhydride that undergoes an O,N acyl transfer to form a tertiary amide. If the active ester is part of an N-alkylamino acid it will form a diketopiperazine. It is demonstrated here that acyl-transfer coupling can assemble highly functionalized bis-peptides bearing a functional group on every monomer.
authors.affiliation: Chemistry Department, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
authors.forename: Zachary Z
authors.initials: ZZ
authors.lastname: Brown
authors.forename: Christian E
authors.initials: CE
authors.lastname: Schafmeister
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D018360:Crystallography, X-Ray; D054659:Diketopiperazines / Q000138:chemical synthesis* / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D013237:Stereoisomerism
chemical_list: D000596:Amino Acids; D054659:Diketopiperazines