title: On-resin head-to-tail cyclization of cyclotetrapeptides: optimization of crucial parameters.
abstract: Cyclotetrapeptides are constrained cyclic peptides whose synthesis is considered a difficult task. A methodology based on on-resin head-to-tail cyclization by anchoring the side chain of a trifunctional amino acid was investigated. A series of model cyclotetrapeptides containing the RGD sequence cyclo(Xaa-Arg-Gly-Asp) (Xaa = Ala, Phe, Phg, D-Ala, D-Phe, D-Phg) was synthesized with no cyclodimerization by-products. An evaluation and optimization study of all of the parameters directly involved in the ring closure was performed.
authors.affiliation: Dipartimento di Chimica Organica Ugo Schiff, Università di Firenze, and CNR-ICCOM, Polo Scientifico, 1-50019 Sesto Fiorentino (FI), Italy.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Alcaro
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Sabatino
authors.forename: Jacques
authors.initials: J
authors.lastname: Uziel
authors.forename: Mario
authors.initials: M
authors.lastname: Chelli
authors.forename: Mauro
authors.initials: M
authors.lastname: Ginanneschi
authors.forename: Paolo
authors.initials: P
authors.lastname: Rovero
authors.forename: Anna M
authors.initials: AM
authors.lastname: Papini
mesh_terms: D003500:Cyclization; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry*; D010456:Peptides, Cyclic / Q000138:chemical synthesis / Q000737:chemistry*; D014320:Triphenylmethyl Compounds
chemical_list: D009842:Oligopeptides; D010456:Peptides, Cyclic; D014320:Triphenylmethyl Compounds; C047981:arginyl-glycyl-aspartic acid